Electric brake problem - looking for answers.

Submitted: Sunday, Jan 19, 2014 at 22:54
ThreadID: 105865 Views:7200 Replies:9 FollowUps:29
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Back in 2010 I bought my parents Mitsubishi Pajero from them when they bought a new tug for their van. They used the Pajero to tow their van. The Pajero has a Hayes Lemmerz Energize iii controller fitted and has a 7 pin flat wiring socket. The trailer brakes worked fine when last used by the Pajero in 2010.

Their new tug has a Redarc brake controller with a 12 pin flat socket and they still have the same van (now with 12 pin plug) and the van brakes work fine behind the new tug. The Auto electrician who wired the redarc controller and new 12 pin plug also fitted a house battery to the van but emphasised that the 7 pin side of the plug was still where the electric brake wiring is.

Now my parents are lending me their van for a couple of weeks and I will be towing it with the same Pajero that was used to tow the same van prior to 2010. The 12 pin van plug didn't fit my 7 pin socket so I have replaced the Pajero socket with a 12 pin one. I simply wired the 7 pin side of the 12 pin socket exactly the same as the 7 pin socket was. My wiring job is definately done properly. Definately.

Guess what? Yep, the trailer brakes don't work, zero zilch nil nothing. All other lights work perfectly. I have removed the covers off the van plug and all wiring is the correct colour in the correct place. The blue service brake wire is right where it should be. I have 12.7 volts at both plug and socket when connected together and the manual brake slide is activated at the controller. I have no reason to suspect that the controller is faulty but I've substituted two other controllers (one that is definately known to be working fine) and still no joy.

Using a second person to acitvate the brakes by using the slide function on the controller:

1. The red brakelight wire has no voltage with slide off (brakelights off) but has over 12 volts once brakelights are activated by the controller. Brakelight connection should be fine?

2. After unscrewing the controllers white earth wire at the vehicle body, the red light on the controller stops working. Screwing the earth wire back in and the controller light works properly again. Earth should be fine or at least good enough to get some brake response?

3. More than 12 volts at blue plug/socket wires with slide fully activated and progressive increase in voltage as slide is progressively activated. I've also checked the blue wires at van wheels and there is also more than 12 volts back there. Power is reaching brakes?

This has really got me stumped. Remember - the van brakes work fine when behind my parents tug.

I have searched this forum and posted on the caravanners forum but no answers yet. If anyone has any suggestions on troubleshooting tips I would be grateful.

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Reply By: Member - Rosco from way back - Sunday, Jan 19, 2014 at 23:08

Sunday, Jan 19, 2014 at 23:08
G'day Martin

How long has the van been sitting without being used?
If it's a while it could be something as simple as the inner face of the drums or the steel in the magnets having a slight rust build-up.
I have found this in the past and also found that a couple of klicks and they all cleaned up OK and bedded back in. First off though there was naff all braking.

May be worth a thought if the van has been sitting for a while.
AnswerID: 524761

Follow Up By: Martin66 - Sunday, Jan 19, 2014 at 23:20

Sunday, Jan 19, 2014 at 23:20
Thanks for the suggestion Rosco. The van is used often. Does the usual migration north for 5 months each winter and was last used in November 2013. In order to eliminate the van as the problem I had my Dad hook his car up to it this morning and the brakes work fine behind his tug.

FollowupID: 806593

Follow Up By: Member - Rosco from way back - Sunday, Jan 19, 2014 at 23:24

Sunday, Jan 19, 2014 at 23:24
Well that leaves me out .... buggered if I know.
FollowupID: 806594

Reply By: The Bantam - Monday, Jan 20, 2014 at 00:13

Monday, Jan 20, 2014 at 00:13
Now these voltages...measured with a digital multimeter?

If there are high resistance joints the digital multi will still read good volts.

try the tests again with test test lamp.

My first suspicion would be that new 12 pin plug.....I loathe and detest those flat plugs.....they are just trash from start to finish....but looks like ya stuck with it.

One of the issues is contact tension, another is the screw terminals.

AnswerID: 524764

Follow Up By: Martin66 - Monday, Jan 20, 2014 at 09:17

Monday, Jan 20, 2014 at 09:17
Yep, using my multimeter. Just working with what I have. Yep a test light would be a good addition to my tool box.

All indicator, tail and brake lights are working with the new socket so it should be ok?

FollowupID: 806605

Follow Up By: The Bantam - Monday, Jan 20, 2014 at 21:49

Monday, Jan 20, 2014 at 21:49
sorry but that is faulty reasoning.
Just because one thing works, that does not mean another thing is not faulty.

Step by step systematic fault finding is what will getbthe job done.

what is happening with the indicators and tail lights has not a thing to do with the brakes.

FollowupID: 806672

Follow Up By: The Bantam - Monday, Jan 20, 2014 at 22:15

Monday, Jan 20, 2014 at 22:15
Correction...what is happening with the indicators and taile lights MAY have nothing to do with the brakes.

FollowupID: 806677

Reply By: Iza B - Monday, Jan 20, 2014 at 08:18

Monday, Jan 20, 2014 at 08:18
Did work and now they don't and the only obvious change is the pug? Frustrating. Can you activate the brakes using the slide control while moving? You seem to be describing the static situation in your troubleshooting. Clearly, the issue is upstream from the van - what voltage do you get in the van side of the plug when the brake pedal in the Paj is depressed?

AnswerID: 524766

Follow Up By: Martin66 - Monday, Jan 20, 2014 at 09:25

Monday, Jan 20, 2014 at 09:25
Yes, activating the slide control while moving and foot off the brake pedal is what I've been doing. No braking at van wheels at all.

I'm getting 12.75v at van side of plug (earth pin 3 & pin 5) with brake pedal depressed. I'm getting a progressive voltage increase up to 12.55v using the slide.

FollowupID: 806606

Follow Up By: Iza B - Monday, Jan 20, 2014 at 17:58

Monday, Jan 20, 2014 at 17:58
If you are getting 12 volts at both pins, there is no effective earth on the car side of the plug, that is, there is no voltage drop across the magnet coil. If you are measuring 12 volts between the pins, the brake magnets should be energising, at least.
FollowupID: 806645

Reply By: Brian 01 - Monday, Jan 20, 2014 at 08:44

Monday, Jan 20, 2014 at 08:44
I didn't see where you mentioned checking the earthing at the rear plug.
Don't just rely on the other lights on the van working as that may be feedback through other globes or via the coupling.
The brake magnets require quite a bit of power and a faulty earth will cause the problems you are having.
Make sure the earthing is absolutely A1.
AnswerID: 524769

Follow Up By: Martin66 - Monday, Jan 20, 2014 at 09:35

Monday, Jan 20, 2014 at 09:35
Thanks Brian, the earth wire just disappears into a harness at the back of the car. Where would I start looking? Does the fact that I'm getting 12.75v at pins 3 & 5 make a plug earthing problem unlikely?

FollowupID: 806607

Follow Up By: Brian 01 - Monday, Jan 20, 2014 at 11:21

Monday, Jan 20, 2014 at 11:21
Martin, if you have a set of jumper leads, connect one of the leadss between the chassis of the van and the chassis of the car, make sure of good contact at both ends.
If an earth fault exists this should make it go away temporarily.
FollowupID: 806620

Follow Up By: Martin66 - Monday, Jan 20, 2014 at 12:24

Monday, Jan 20, 2014 at 12:24
Thanks Brian, just tried your suggestion, still no good. :(.
FollowupID: 806625

Follow Up By: The Bantam - Monday, Jan 20, 2014 at 22:05

Monday, Jan 20, 2014 at 22:05
Um be carefull of the asumption that the chasis of the van is earthed.

There are a multitude of earthing issues and variations....there are also many misconceptions about earthing in DC systems. systems.....sometimes I think is is wise to do away with the idea of earthing and speak in other terms.

First check that the electrical system in the van does or does not have a connection between the chasis and negative wires.

Second check that the negative wire in the socket on the car is well connected to the chasis and the chasis is well bonded to the battery negative.

There are many rubber isolations in vehicles....there should be straps bonding various parts of the vehicles to each other and the negative terminal of the battery.
Often..this is not the case or these bonds have failed.

Because the quality of the chasis bonds can vary and it is difficult to test this with instruments normal people have.
the only sure way is to inspect these earth bonds and make sure clean contact is there.

One thing with hub mounted electric brakes is that there may be an unreliable bond between the axle and the chasis.....realy there should be some sort of wire for the negative retrun from the brake magnets.

If you cant confirm or trace an earth...make a new one.

HMMM...there may be an earthing issues her..may be.

for example. IF the trailer does not have a good or any bond between the chasis and the negative wire in the plug....AND the brakes are earthed tru the chasis.

The parents tow vehicle may be providing a good earth thru the tow bar and tow ball........the original posters car may not be providing this tow ball earth.
OR, some such variation on the theme.

Just because it works ...don't mean its right.

FollowupID: 806674

Reply By: Ross M - Monday, Jan 20, 2014 at 10:30

Monday, Jan 20, 2014 at 10:30
Have you used a multi meter to see if their is a resistance between the blue wire in the plug and the white wire?

That will tell you if the circuit of the vans braking is actually complete.

Because you get more than 12v at the van wheels, due to wiring resistance and the metering out of pulsed energy to the wheels from the controller, it is unlikely it will be much over 12v if at all.
Because of that relatively high reading I would immediately suspect the return, ie earth, white wire, isn't connected to the earths, neg side of the magnets OR the white wire is cut somewhere and isn't actually touching pin 3 in the plug.

If you use a battery charger or can use battery power direct to pin 5 +ve and pin 3 -ve you should immediately hear the magnet grab the drums. CLACK.
So if there is no connection by meter test, ie continuity, and with battery supply to it you don't hear the magnets and also there will be an induction spark as the power is removed, it would seem the magnet circuit isn't one at all.
AnswerID: 524773

Follow Up By: John47 - Monday, Jan 20, 2014 at 10:50

Monday, Jan 20, 2014 at 10:50
Had a similar problem and rang manufacturer of brake controller who said very important that earth from brake controller MUST be wired to earth of CAR BATTERY NOT chassis. Definitely solved the problem.

FollowupID: 806613

Follow Up By: Martin66 - Monday, Jan 20, 2014 at 10:58

Monday, Jan 20, 2014 at 10:58
Thanks Ross, Sorry, I've just tested voltage again at van wheels and it reads 11.7v with brake pedal depressed.

Given that the van brakes work perfectly behind my fathers car, I would be surprised if the problem lies in the van. Not impossible of course but would be unlikely.

I will go out now and reroute the brake controllers earth wire up to the battery.

I'll be back in an hour or so :)

FollowupID: 806614

Follow Up By: Ross M - Monday, Jan 20, 2014 at 11:18

Monday, Jan 20, 2014 at 11:18
It is likely the actual brake controllers earth wire is OK but the trailer plug earth wire which isn't seeing the neg of the battery.
Ideally they should all be locked to neg and as John 47 said.
If it is the brake controller earth wire at fault the controller shouldn't be able to meter out pulses to vary the signal as it has no reference earth/neg if sus.
FollowupID: 806617

Follow Up By: Martin66 - Monday, Jan 20, 2014 at 12:16

Monday, Jan 20, 2014 at 12:16
Rerouting the brake controllers earth wire hasn't fixed the problem.Ross, if the plug earth wire wasn't seeing the neg of the battery, is it possible that I still get 11.7v at van wheels?
FollowupID: 806624

Follow Up By: Brian 01 - Monday, Jan 20, 2014 at 12:43

Monday, Jan 20, 2014 at 12:43
Martin, in your answer to me you said that you were getting 12.75v to pins 3 and 5 but that doesn't confirm that it goes right through to the brakes.
In your post above you say that you are getting 11.7 volts at the wheels.
This should be sufficient to activate the magnets, is this not happening?
Am I understanding you correctly?
Be aware that pin 10 on the 12 pin plug is also an earth. Is it possible that is the pin that has been used for the brake earth and which obviously won't be connected to your earth via your 7 pin plug unless it has been bridged in the 12 pin plug, maybe worth a check.
Still doesn't explain to me why 11.7v is not energising the magnets though.

FollowupID: 806626

Follow Up By: Martin66 - Monday, Jan 20, 2014 at 12:53

Monday, Jan 20, 2014 at 12:53
Brian, your summary is correct and this is why I am absolutely stumped by this.

Yep 12.7v at plug and 11.7v at van wheels but magnets don't activate. However, when we connect to my Dads car the magnets activate.

Pin 10 is blank on both the van plug and the socket on my Dads car.

I have just booked it in at an auto electrician for tomorrow. I'm a bit disappointed about this as I don't like to let a challenge get the better of me. I will keep racking my brain until then.

Thanks for your suggestions.

FollowupID: 806627

Follow Up By: Ross M - Monday, Jan 20, 2014 at 16:42

Monday, Jan 20, 2014 at 16:42
From what you have described the definite checking of the controllers earth not making a difference confirms what I said,
In order for the controller to meter out energy it must have that earth correct and it is still correct.

The earthing I mentioned is the same concept as Brian mentioned, the earthing of the base white wire may not be connecting to the battery negative.

Do you have both plug and base together but OPEN and can physically see the correct coloured wires on the correct pins match each others position in both the plug AND base?

Dealing with mirror reversal and frack to bunt can sometimes be an issue.

Just for the exercise, run a spare wire from the PIN 3 of base to the batt neg and see if it improves.

FollowupID: 806637

Follow Up By: Martin66 - Monday, Jan 20, 2014 at 18:27

Monday, Jan 20, 2014 at 18:27
Hi again Ross, I have a live Anderson plug on the back of the Paj that runs directly to the battery. Using a spare Anderson connector I have made up a negative wire from the Anderson plug to pin 3. No joy.

Yes, all colours match and I've traced all wires to ensure correct placement.
FollowupID: 806648

Reply By: Martin66 - Monday, Jan 20, 2014 at 18:34

Monday, Jan 20, 2014 at 18:34
Now I have some significant information for you.

When testing all the lights on the van, I tested them separately. I have now tested the hazard lights and tail lights together and the tail lights are also flashing moderately (opposite sequence to hazards).

I replaced the connector of what I believe to be the earth wire at the van chassis and that has made only a slight difference. Using a file I scraped the surrounding area and hole as well as the bolt, washer and nut. I cut the old round connector off, stripped to expose fresh wire and crimped a new round connector to the earth wire.

Now I'm thinking maybe I should pay some more attention to the issue being van related?

AnswerID: 524816

Follow Up By: Member - LeighW - Monday, Jan 20, 2014 at 20:17

Monday, Jan 20, 2014 at 20:17
I can't remember if you tried this but try earthing the car chassis to the van chassis and see if it makes a difference?

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FollowupID: 806666

Follow Up By: The Bantam - Monday, Jan 20, 2014 at 22:13

Monday, Jan 20, 2014 at 22:13
martin mate you have an earthing problem ...guaranteed.

This may not however be the only problem.

Do not assume anything is correct.....lots of faulty and incorrect things work...um ..er..just fine.

FollowupID: 806676

Follow Up By: Brian 01 - Monday, Jan 20, 2014 at 23:01

Monday, Jan 20, 2014 at 23:01
This is an earthing problem Martin.
At the risk of boring you with what you may already know, what happens when you have a faulty earth to your lights (let's say at the plug) is that the current path which would normally be through the globe filament to earth now becomes convoluted because that earth is missing, the return takes an extenuated trek through any other globes that are connected to the same earth and this generally includes back through globes in the vehicle to get to a good earth.

An example of the circuit route may be:- 12v to tail light - poor earth so current goes through stop filament - back to car via stop light wire to stop filaments (plural as there is more than one) on car - through filaments to good earth on car.
The filament with the lowest wattage (highest resistance, ie tail light,) will glow brightest, in fact just about the same brightness as if no fault existed.
This is because more voltage, in the above case almost all of the voltage, will be dropped across the tail filament.
Switch a few on together, say indicator and tail and every time the indicator globe gets 12v from the flasher it effectively shuts down the pseudo return path for the tail light (12v+ve on both sides) which will go off. It will normally be the indicators on the car and the tail light on the van that alternate.
When the opposite occurs the tail light will again glow.
This is the effect you are seeing.
Now, the brake magnets have far more wattage than the light globes which means they have less resistance, therefore the globes are dropping all the voltage and the magnets are not energising.
The reason that you were seeing that 11.7v at the brake magnets was because the globes were giving you a return path with a small additional voltage drop but the resistance was too high to allow sufficient current to energise the magnets.
Fix the earth and the problem will go away.
Because of what is happening with the lights we can be reasonably confident that all of the lighting earths and most likely also the brake earth are connected together, so you just have to find where that earth is discontinuous either on the van or the car.
Have you tried that jumper between the 2 chassis since cleaning the earth?
Possibilities are:-
1. The earth in the van plug is not connected to the van chassis.
2. The earth from the lights etc, is not connected to the van chassis.
3. The earth from the lights etc, is not connected to the earth pin in the plug on the van.
4. The two plugs are not connecting properly.
5. Any combination of the above.
You are getting a good earth indication at the car plug, so the problem is most likely in the van.
That's all I can offer at present.
Let us know what you find.
FollowupID: 806683

Follow Up By: Martin66 - Monday, Jan 20, 2014 at 23:21

Monday, Jan 20, 2014 at 23:21
The tail lights are still flashing when hazards are also on and the 2 chassis are connected.

I'm not absolutely sure that the earth connection that I replaced is the other end of the pin 3 wire because it runs through the draw bar (chassis). Is it likely to be?

I haven't removed the van rear lights yet to do maintenance there. Are the earth wires there likely to be attached to the chassis or do they run within a harness back to another earth?

FollowupID: 806687

Follow Up By: Brian 01 - Tuesday, Jan 21, 2014 at 07:38

Tuesday, Jan 21, 2014 at 07:38
Are you sure that jumper is making good contact at both ends?It's impossible to tell from this distance just how the van has been wired.
Van builders are a strange bunch when it comes to wiring.
I would expect there to be somewhere on the van where the wire from the front exits the drawbar and splits into the various directions for brakes, lights etc., and that's the most likely spot for joins, earth to chassis, etc. to be done.
The usual spot of choice is near the wheels.
See if you can locate that spot as it is most likely there that you will find that the wire from pin 3 is not properly terminated.
Although unusual, it is conceivable that the brake earth goes back to the lights before being connected to the main earthing conductor.
Other than the above solution, the easiest step may be to simply splice into the return wire from one of the brake magnets and connect it straight to the chassis somewhere near the wheels.
Odds are that everything will work after that as all the returns may then go back through there, provided of course that there is actually a connection from your car earth to the van chassis, Keep that chassis jumper in place for the time being to be sure.
If it all works, then remove the jumper and see what happens.
Once you get it all working you can then tidy it up.
FollowupID: 806693

Follow Up By: Martin66 - Tuesday, Jan 21, 2014 at 10:00

Tuesday, Jan 21, 2014 at 10:00

The problem has now been solved and I will update with the outcome but I'll address your suggestions here.

Yes it is possible that the jumper leads weren't making good contact even though I tried several points of connection on both car and van. I attached car side to various points including unpainted towbar mounting bolts on car. At the van I used various points along the draw bar including the jockey wheel holder and end of draw bar.

The point at which the van wiring splits and goes in various directions is inside the drawbar. The house battery and box which were retrospectively fitted in 2010 by and auto electrician are located on the drawbar so wiring has been altered to feed in and out of the box and drawbar. Under the van, at the end of the drawbar there is a harness that comes out and goes straight through the flloor to the inside of the van, there is that single white (earth) wire and two blue wires for the brakes.
FollowupID: 806698

Reply By: Martin66 - Monday, Jan 20, 2014 at 23:04

Monday, Jan 20, 2014 at 23:04
Thanks Bantam for all your replies. You have sort of put some perspective into all of this. You have probably worked out that my auto electrical knowledge is very basic and I appreciate the polite way in which you have responded to some of my ideas.

As I said earlier, I have the car and van booked in at an auto electrician tomorrow which is probably the best thing for me. Hopefully a more thorough job will be done than I would have been able to do myself and I can return the van to my Dad with some improvements. :)

I will report back to let you all know of my outcome.

AnswerID: 524831

Reply By: Member - LeighW - Tuesday, Jan 21, 2014 at 09:37

Tuesday, Jan 21, 2014 at 09:37

I know this probably not going to help you but you really need to just revert to basic fault finding skills.

Your trailer plug has several pins in it as does your cars plug, as you know each pin is assigned a task. If you haven't already, get your self a picture showing the wiring of the plug.

Get your meter and using the volt meter, with positive probe on plug and negative on a good earth operate the turn signals, brake, lights etc one at a time and check
that the associated pin and only that pin becomes active on the cars plug.

Next using the ohm meter in low voltage mode ensure that you see 0 ohms or at the very minimum less then and 1 ohm between the plugs earth pin and either the earth common in the car or the vehicles chassis.

If they all check out do exactly the same on the van also ensuring all wires go to the correct numbered pin.

It does sound like an earth fault so you be able to speed up the process, remove one of the turn indicator lights on the van, remove globe and connect probe to what you think is the turn signal wire, and the other to the associated turn signal wire in the trailer plug check that you get zero ohms, if you don't then try the other pin globe pin, when you get the reading you have located the turn signal pin on the globe for sure. Also check that you don't get a reading on any other pin. As you have now identified the turn signal pin the other pin (assuming it only has two pins) or the body of the holder if it only has to be the earth wire.

Again test with meter to earth pin on plug if the readings are good the earth must be good.

Also move the trailer connector around whilst testing to ensure there is any broken wires in the cable, some times they get stretched and short out.


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AnswerID: 524838

Follow Up By: Martin66 - Tuesday, Jan 21, 2014 at 10:06

Tuesday, Jan 21, 2014 at 10:06
Leigh, you are onto something and I have been wishing that I have more knowledge on how to use the ohms functions on the multimeter.

Thanks for your advice. The problem has been fixed by the auto electrician so I wont need to follow your ideas. I will now get on with posting the outcome.

FollowupID: 806699

Follow Up By: Member - LeighW - Tuesday, Jan 21, 2014 at 10:09

Tuesday, Jan 21, 2014 at 10:09
No Problem, glad its sorted, while your there get them to give you a quick intro into ohm meters etc, sure they wouldn't mind.


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FollowupID: 806700

Reply By: Martin66 - Tuesday, Jan 21, 2014 at 10:27

Tuesday, Jan 21, 2014 at 10:27
OK, problem fixed at a cost of $65 (half an hour for labour) at Tuggeranong Auto Electrics.

It was an earthing problem. Back in 2010 when my Dad had the brake controller and house battery fitted to his new tug the vans plug was changed from a 7 pin plug to the 12 pin plug. Early on in my fault finding, before I posted here, I opened up the plug on the van to look at the wiring. In addition to the normal 7 pin side there were wires at pins 8, 11 and 12. No wires at pin 10. Looks like no earthing on those 5 pins but just to be sure I rang the auto electrician who did the work back in 2010. Of course he couldn't remember the actual installation but he did categorically say that there is no way they would have done any wiring through the 5 pin side of the plug for the trailer brakes.

Well, turns out that pin 11 (fog lights?) has a new earth wire. It is blue. So the solution was to fit a new earth wire at pin 11 on the Pajero. All the original 7 pin wiring was still in place but it seems the earth wire at pin 3 has some issues or was made redundant when the controller and house battery were fitted in 2010.

Some of you have put considerable time into typing up your suggestions so I really want to say thanks for your help. It has been much appreciated and the tollerence of my lack of skill has been very high. Thanks heaps.

AnswerID: 524840

Follow Up By: Brian 01 - Tuesday, Jan 21, 2014 at 11:10

Tuesday, Jan 21, 2014 at 11:10
Glad you got it sorted Martin.
You did mention very early on that you were getting an earth at pin 3 on the car.
FollowupID: 806701

Follow Up By: Martin66 - Tuesday, Jan 21, 2014 at 11:30

Tuesday, Jan 21, 2014 at 11:30
Yes, still an earth of sorts at pin 3 but not sufficient for brakes to work properly even though I was getting 11.7v at van wheels.
FollowupID: 806702

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