Fuse #8 Issues
 

I have been trying to figure out why everything on Fuse #8 will not work for weeks. It includes wipers, fresh air blower, cig lighter, and horn. I have tried sanding any muck off of the fuse area, replacing the power relay, checked for loose wiring...etc..all with no luck. Is there a specific ground point for this fuse or ? Any help would be appreciated as its hard to drive in the rain..

Your Fresh Air relay, (J13) in not working.
Phil

oops, I mean the Fresh Air relay "is" not working. It feeds all the power for the other items.
Phil

OK, I'm not scolding you, but - the first step in diagnosing a circuit problem like this is to get the schematic (right on this web site) and trace the circuit with your DMM. If you do this, you will inevitably find the problem. It's tedious, but that's how the pro's do it, too!

Many 914's have had some wiring atrocities done to them by their various owners. You can only find these by getting in there and verifying that what the wiring diagram says is what is actually there!

Personally, I prefer the old-style schematics to the current flow diagrams, but from what I've heard, if you can get used to the current flow notation, it's faster to use these to debug problems.

Identify the systems that are sourced through fuse 8 (which gets power from the ignition switch when turned to "on"). Any short in these systems will blow fuse 8. Isolate each system to locate the short. Note that there are significant differences in the systems sourced by fuse 8 in the early ('70-71) and later cars. Use the right diagram at the PP site for your car!!!

Happy tracing! :D

S8 gets it's power from the ignition switch via J13(fresh air relay). If J13 does not energize (for whatever reason, bad relay, coroded contacts or connections, broken connection from the ignition switch, etc.), all of the symptoms that tiramisu describes fails. The first thing I would do is pull relay J13, use contact cleaner on the pins and sockets, stick it back in. If that don't work, replace J13, if that don't work, pull out the multimeter and check that voltage is available at J13 when the ignition switch is on, etc., etc.
I always go for the likely faults first, if it don't pan out, then I go to formal trouble shooting. Usually saves a lot of time.
Phil

Don't forget the convenient spare round relays. There's one on each side of the front trunk (as long as you don't need the headlights to pop up), and a couple on the relay board. (Rear window defogger and heater blower relay--or if your 914 is a 1.8 or is carbed, any of them!)

--DD

Thanks for the ideas. I tried swapping out the relay again with a bunch of spares I had..still no luck. I got a little spark when I almost plugged it in wrong so I guess its getting power. I went down and bought a MM..now I gotta figure out how to use it...

Please post on how you finally fixed this problem. I'm having kind of the same issue. Everything on Fuse #8 seems to work on and off whenever it wants to. I swapped the fuse and the power relay to no avail. I bet it's a loose ground wire somewhere. Anyway, let me know what you find. Thanks

Don't forget that the voltage supply to fuse 8 comes from the ignition switch, which often is the source of many 914 electrical problems. From the symptoms you describe, the switch sounds suspect. Try wiggling your key slightly and see if it causes the accessories on fuse 8 to go on and off. The simplest voltage test you can do is to turn the key to "on" and measure the voltage at fuse 8. If you don't see something around +12 V, I'd suggest looking at the ignition switch. Again, try wiggling the key slightly and see if the voltage drops to zero. Another place to look is the power junction that is attached to the side of the support for the fuse box. It's a brown phenolic piece that has three red wires attached to the top of it - be careful! It's wired directly to the battery, make sure you do not accidentally short any of the wires to ground.

Oh, that's what that thing on the wiring diagram is!!! I've always wondered about that.

Note that it isn't present in the later car (73+, not sure about 72).

--DD

Just to clarify, if there is no voltage on fuse S8 when the ignition is on, it is because relay J13 (the fresh air relay located on the back of the fuse panel) is not energized, therefore causing all of the symptoms listed by tiramisu.
If J13 will not energize, it is either defective or it is not getting power from the ignition switch.
Phil

Is that for the post-'71 cars? I'm sorry, but I have myopia when I look at those diagrams, seeing only my car's year. The '70-'71 cars have voltage on fuse 8 anytime the ignition is turned on.

Yup, I just looked at it, you're right. On the later cars, fuse 8 depends on the relay being switched on before voltage is present at fuse 8. As noted before, there are significant differences in the wiring over the model years.

Well I got it all working..it turns out I was working on the wrong relay. The local 914 master came over and determined what relay was correct..popped it out and replaced and *boom* I have wipers :) Thanks for everybodys input.

MM

So you have a 914 Master nearby? And you even try to troubleshoot it on your own?!!?

I would keep a lot nice microbrews on hand and have that guys cell number handy at ALL times!!!