Fuse Problems?

[Azguy238]

I recently purchased a 1976 914 on BAT. It arrived a couple of days ago. The stop lights, tail lights, turn signals and tach don't work (as well a couple of others things). The Alternator light stays on while the engine is running. I noticed that the 4th fuse from the right was bad and replaced it. It immediately blew. Tried again....blew again. Anyone have any thoughts as to where I should start? Thanks, Wayne

[Dave at Pelican Parts]

That's fuse #9, and it supplies power to about 3/4 of the things in the car that use "switched power". The "upstream" side of it gets fed from terminal "X" on the ignition switch, which also supplies the relay board and possibly another branch. (The wiring diagram says it powers the Dreaded Seatbelt Interlock Relay, which should not be present on a 76.)

That's stuff that is not protected by the fuse, BTW, because it is all on the "upstream" side of it. The "downstream" side has several branches.

One branch (red/white wire, or red with a white stripe) sends power to the gauges in the dashboard. This includes one side of the alternator light, which will make it come on when the engine is running. And will prevent the battery from charging.

One branch (red/white) feeds the emergency flasher switch, and everything that gets power from it when the switch is not on. (Yes, I know that sounds weird.) Which includes the turn signals.

The third branch (black/yellow) sends power to the brake light switch on the pedal cluster, and also (red/white) to the oil temp gauge and voltmeter in the center console (if the car has those), and (gray/brown) to the back up lights and back up light switch.

If anything "downstream" of the fuse is shorted to ground, the fuse will pop and all of that "downstream" stuff will no longer work.

Step one is to double-check the connections on the turn signal buckets. Jeff Bowlsby's Tech Notebook has very handy diagrams, which I will add here:






If you make sure those are correct and you still have issues, you will have to try to isolate various parts of the circuit to see if you can narrow down where the short to ground is.

I suggest also checking or maybe just unplugging the license plate lights. Those caused me a whole bunch of trouble once after a body shop returned the car to me.


Finally, a really good resource to have on hand is the Haynes workshop manual for the 914. It's very much not the best workshop manual I have seen, but it is a word-for-word and photo-for-photo copy of about 85% of the factory workshop manual. It's also a lot less than the $350+ set of factory manuals, and takes up a ton less shelf space. It even has wiring diagrams, though not in color.

--DD

[Emo993]

I just did mine after 25 years of storage. Had to replace headlight switch, then blinker relay and then the turn signal/wiper switch in the steering column. All good and not to hard to do...after the fact. Best, Mark

[Azguy238]

Thank you Dave for all the help. Now my work is cut out for me. I'll keep you posted

[earlyaircooled]

Is fuse #9 only suppose to be 8 amps? seems like a lot going on for such a low amp fuse