Fuse blowing

Submitted: Thursday, Nov 13, 2008 at 19:17

ThreadID: 63500 Views:5960 Replies:3 FollowUps:0

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Mudripper

Hi all, this is a good question for all the sparkies out there. I have a 1976 HJ45 Landcruiser and keeps on blowing the "ENGINE" fuse. I had the alternator overhauled today, a new voltage regulator installed last week, so the charging system works well except that I have to get it adjusted. The fuse is a 15 amp and blows only when the engine is running. We connected an ammeter and when the ignition is ON we have a reading of around 3.9 amps. When the engine is started the amperage goes up to 17 amps and with the engine speed increasing, goes up further to 20 amps and beyond. Obviously beyond the fuse's capacity. However, the charging system still operates even with the fuse blown, in fact everything works. I don't have a wiring diagram, neither could I get one off the Internet. What's going on here? The wire that goes to the fuse is green with a red stripe. What does the "ENGINE" circuit include (it's all quite ambiguous)?

Any help greatly appreciated.

Cheers.

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Reply By: Dunaruna - Thursday, Nov 13, 2008 at 20:40

Thursday, Nov 13, 2008 at 20:40

Probably a glow plug circuit issue (quite common back then). Try re-doing the amp tests with the glow plugs disconnected (or pull the plug from the relays).

AnswerID: 335100

Reply By: Affordable Batteries & Radiators - Thursday, Nov 13, 2008 at 22:56

Thursday, Nov 13, 2008 at 22:56

Also check the wiring harness for any spot that may have rubbed through over the last 32 years.

Regards

Derek.

AnswerID: 335141

Reply By: Bob Y. - Qld - Saturday, Nov 15, 2008 at 08:16

Saturday, Nov 15, 2008 at 08:16

Muddy,

Used to drive a 75 series with 2H motor, and it had this problem, intermitently. Worst occasion was turning onto the low-level bridge in Mt Isa, when engine stopped mid-turn, and had to use starter motor to get the vehicle off the road.

Turns out there was a short in right hand turn signal, which blew the "engine" fuse. As Derek said look for any wear, where ever wiring looms run over chassis, or across cross-members. Might take a while to find, and doesn't need to be much of a wear mark, to cause a short.

Good luck,

Bob.