Electric brake troubleshooting

Submitted: Thursday, Feb 25, 2010 at 15:29
ThreadID: 76326 Views:8402 Replies:6 FollowUps:7
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I have a 1982 Viscount Grand Tourer pop-top. I have upgraded the override brakes to electrics. Mechanically everything was easy.

I got the local auto electrician to install a Tekonsha Prodigy brake controller to the tow vehicle - a 2004 Kluger. Meanwhile I connected the designated blue wire in the Viscount harness to the brakes.

Took the unit out on the road in a nearby subdivision and did a test run and everything worked correctly.

Final touch was to clamp the override section of the hitch to disable the van from activating the brakes the old way.

First trip was down the mountains (from Orange NSW) to the Lane Cove van park at North Ryde. On the way we noticed that the Prodigy was flashing red and giving the warning "Overload". The brakes became a bit grabby as though pulsing on and off - fortunately we were travelling slowly at the time.

Finally back in Orange I went back to the auto electrician whose diagnosis was the controller - he "doesn't like" Tekonshas. He reckoned I needed something I could adjust the Gain, so I replaced the Prodigy with a Voyager unit.

Similar problem with the brakes grabbing and releasing - I guess you'd call that overload.

I have dialed down the gain so much that I decided I should take the clamp off so that the override braking is reactivated, while I only use the electrics by sliding the lever across in manual mode.

What am I missing here? Is there something wrong with how the electrician has wired the controller? Is it the wiring? Or is it the settings?

Any help would be appreciated.
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Reply By: Mikelb - Thursday, Feb 25, 2010 at 16:35

Thursday, Feb 25, 2010 at 16:35
Check where the auto electrician picked up the brake light activation wire. he may have picked up the brake light at the brake light switch. The best way is to run a wire from the brake light connection at the rear 7 pin plug, back to the electronic brake unit. This means that you are picking up the power for the brake light after Toyota's little black box that plugs into the loom for you 7 pin plug. I have a V6 Rav4 with a Prodigy and have no problems at all. I had a Kelsey Hayes prior to the prodigy and it worked well, but I have found the Prodigy much better.
This may help
AnswerID: 405965

Reply By: Tenpounder (SA) - Thursday, Feb 25, 2010 at 18:00

Thursday, Feb 25, 2010 at 18:00
Hi there. Replacing a Prodigy with a Voyager sounds like bad news to me, having spent good money to do the opposite. The Voyager has had far more problems generally than the Prodigy, and I truly doubt that this swap would help.
I suggest your electrician is talking through his hat in saying the Prodigy gain can't be adjusted.
But as to whether it is the brakes that are set up incorrectly and wired correctly, or else the controller wired wrong, I wouldn't want to say. But I wouldn't overlook a check of the brake wiring before putting too much emphasis on the controller.
AnswerID: 405982

Follow Up By: Tenpounder (SA) - Thursday, Feb 25, 2010 at 18:12

Thursday, Feb 25, 2010 at 18:12
PS I am suspicious about your advice that, with your system, you have electrical brake actuation via the controller AND mechanical actuation of the trailer brakes. Has your electric brake installation been checked by a professional?
FollowupID: 675661

Follow Up By: Lex M (Brisbane) - Thursday, Feb 25, 2010 at 18:57

Thursday, Feb 25, 2010 at 18:57
Are the override brakes hydraulic or cable?
FollowupID: 675676

Reply By: Ray - Thursday, Feb 25, 2010 at 18:55

Thursday, Feb 25, 2010 at 18:55
Now this is a real teaser or someone is having someone on. The mechanisms for (as far as I know) are completely different for electric brakes and hydraulic brakes.
There is one thing though. A few years ago I had a Viscount. It was a tandem axle but only had brakes (electric) on the leading axle. The tailing axle was just a free wheeler. If this set up is the same as mine they MAY have fitted electric brakes on the trailing axle and left hydraulics on the leading axle but this is very unlikely
AnswerID: 405992

Follow Up By: Member - James N (NSW) - Thursday, Feb 25, 2010 at 20:59

Thursday, Feb 25, 2010 at 20:59
Okay, for the doubters...

They were mechanical override brakes. I bought the electric brakes on eBay, and as I said, they just bolted on. As the mechanical override system uses the handbrake system, there was no problem there, the handbrake works as it always has.

What gave me the idea was that there were the wires at the brakes, not connected of course, but available for use.

The connection was easy, the brakes tested fine. As for "disabling" the override brakes, I put a metal pipe clamp in the part of the trailer hitch that slides forward with mechanical override brakes (as the original stopper had disappeared under previous ownership) to leave the handbrake still working, but not have two competing braking systems.

My question is covering two issues. I have heard some say that the wiring through the 7 pin plug and in the standard 7 core cabling is too light. One suggestion was that it was better to run heavier wire through a spare connection on a 12 pin connector so that heavy duty wire runs to the brakes.

This then seems to me to suppose that there should be heavier wire to the brake lights anyway.

Which brings me back to my concern that the installation on the car is the cause of the problem. This, I think, was Mike's point. However, I am unclear as to where he means for the wire to be connected. Should there be a long wire from near to the brake light back to the controller? What about voltage drop in that instance?

The auto electrician I went to does not strike me as particularly knowledgeable about fitting electric brakes, but there are few choices out here.

I could take the van to either Bathurst or Dubbo as there are specialists there, but I'd like to know what questions to ask first.
FollowupID: 675719

Follow Up By: Tenpounder (SA) - Thursday, Feb 25, 2010 at 21:27

Thursday, Feb 25, 2010 at 21:27
OK. This is beyond amateur advice. Your system needs to be checked over by a professional. There's no system that allows both mechanical override and electrical braking off the same shoes and linkages, so there's something odd about your arrangement.
Forget about heavier brake light wires, please, and get the system inspected.
FollowupID: 675726

Reply By: Member - Barry (NT) - Thursday, Feb 25, 2010 at 21:08

Thursday, Feb 25, 2010 at 21:08
Are you 100% sure you have picked up the "blue" Viscount wire and it IS connecte dto brakes.

Why would a caravan have a "blue wire" if it had override brakes???

I would wire your new electric brakes via new wire to the tow vehicle to ensure a 100% secure and dedicated connection before anything else

just a thought
AnswerID: 406023

Follow Up By: Member - Barnray (NSW) - Thursday, Feb 25, 2010 at 21:50

Thursday, Feb 25, 2010 at 21:50
I think you have a short to earth after the controller, If the system is set up properly it will have a circuit breaker in the main lead to the controller, if there is a short it will give you a pulsing activation on the brakes. Branray
FollowupID: 675734

Reply By: Lex M (Brisbane) - Thursday, Feb 25, 2010 at 21:56

Thursday, Feb 25, 2010 at 21:56
OK. Let's get this straight.

If the controller flashed red an displayed "overload" it must have been a Tekonsha P3.

Overload indicates too much current in the brake circuit. A short in the wiring or some such thing.
This would cause the controller to shut down the braking and then try to recover, which would make the brakes pulse on and off.

I'd be looking very carefully at that "blue wire" in the caravan. It may not be what it appears to be.
Alternatively you have a shorted activation coil or similar in the brakes.
If the brakes were working even if only intermittently, I would not worry about the size of the wiring until the overload condition is resolved.

I don't understand why you would swap out a P3 for a voyager. The P3 was trying to tell you something.

AnswerID: 406040

Follow Up By: Member - Barry (NT) - Thursday, Feb 25, 2010 at 22:45

Thursday, Feb 25, 2010 at 22:45
yes Lex this is what I was alluding to above (short and "blue" wire use/purpose).

fault find the system first not just a component (especially when 2 controllers have been fitted and have not resolved the problem)
FollowupID: 675745

Reply By: Member - Graham H (QLD) - Thursday, Feb 25, 2010 at 22:06

Thursday, Feb 25, 2010 at 22:06
Firstly the sparky didnt have a clue if he said the Voyager was better.

Thats like replacing a Rolls Royce with a model T

Mine is connected like this on a 100ser

Red wire connected to cold side of brake light switch above pedal. (no voltage drop in 500mm of wire)

Black to earth

Blue is connected to a double 4.8mm wire back to pin 5 on a large round socket.

White ??? but its in the right place. as per fitting instructions. Power from battery???

The unit should show 2 little dots till about 5mins after turning car off.

when connected to van should show C. if fault NC

When brakes applied shows varying voltage readings.

I would get a multimeter and check where the wires actually go to and from on the van as it is extremely unlikely that the van would use blue for brakes it didnt have when new.

I think the brakes are registering voltage that is going somwwhere else in the van.

You may well end up with large clouds of smoke and not from the brakes either

The power circiut should have a self resetting circuit breaker in it as well

Check out the wiring in the van and make sure its on pin 5.

AnswerID: 406044

Follow Up By: kend88 - Thursday, Feb 25, 2010 at 22:38

Thursday, Feb 25, 2010 at 22:38
Just for the record, aren't Prodigy and Voyager both Tekonsha's, with the P3 being the further upgrade.
I have never heard of a problem with a correctly installed Prodigy or P3, but the Voyager did have a few problems.

FollowupID: 675743

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