electrical problems

[81headache]

My car is running and driving I am very happy and thanks to all that helped me get here now for some annoying things.

1. Headlights...they go up but not back down not huge deal for I use manual knob in morning to put them down.

2. when i replace the blown fuse for cig lighter it just pops as soon as i turn key..I don't smoke but I think may be affecting other things.

3. passenger side window doesn't go up or down a new switch was installed last year I'm not sure if it was working then or not...could this be related to blown cig lighter fuse.

4. finally the heater ac not working if i move heater switch to hot it will let hot air out but fan doesn't work nor does anything happen when push ac switch..again could this be related to blown fuse and short somewhere.

I have checked all the fuses that may correspond with those and any other issues all fuses intact aside from one that has some sort of short.

Thanks for any assistance or ideas

[harborman]

Is the cig lighter itself in or not?

Window switch. These are cheap switches and known to go bad often. From my experience when they go, they have a different feel when pushed in.

Many of your problems have been answered on here. Just do some searches here any you will find many detailed posts.

[MainePorsche]

Originally Posted by 81headache

My car is running and driving I am very happy and thanks to all that helped me get here now for some annoying things.

1. Headlights...they go up but not back down not huge deal for I use manual knob in morning to put them down.

Get a new headlight relay. Even though the headlight motor has position sensors internally, these units are robust and don't often fail. The headlight relay is not robust. Swap one out with a buddy who has a similar year car for confirmation.

2. when i replace the blown fuse for cig lighter it just pops as soon as i turn key..I don't smoke but I think may be affecting other things.

The fuse is not the reason, but the message that something is amiss. It may affect other things if it is corrupting a ground. It is shorting some where. You need to look. Remove passenger side center console carpet panel and check the wiring.

3. passenger side window doesn't go up or down a new switch was installed last year I'm not sure if it was working then or not...could this be related to blown cig lighter fuse.

The switch is probably good if it is new. While center carpet panel is off check the wiring for the window switch. It lies there. The windows also have a relay, but failure would affect both windows. My money is on the wiring. Also, see recent window thread I posted to.

4. finally the heater ac not working if i move heater switch to hot it will let hot air out but fan doesn't work nor does anything happen when push ac switch..again could this be related to blown fuse and short somewhere.

I wrote this for someone once upon a time.


There is no "11 relay". The device in position XI is a spike suppresor.

The power to operate the A/C compressor clutch comes thru fuse #17 to Relay X, the blower relay. If the A/C blower works, the fuse and this relay are good - if the blower doesn't work, neither will the compressor.

From the relay, power goes to the A/C switch on the dash.

From the A/C switch, power goes to the A/C control head. There is a small relay in the control head that controls the power to the compressor clutch - this relay can fail.

The power then goes to the antifreeze switch on the A/C evaporator. If the evaporator gets below freezing, the switch opens, cutting off the compressor. Remove the plastic shield at the base of the windshield under the hood (careful - it breaks easily)and find the switch near the center of the windshield. Check for 12 vdc on both connections on the switch (ignition on, A/C on, air distribution lever on). If there is power on both, everything so far is OK. If there is power on one terminal, tha freeze switch is bad. If there is no power on either, fuse #17, the fan relay or the A/C controller relay may be bad. If the blower works, but there is no power here, the controller relay is the usual suspect.

From the freeze switch, power goes back to the central power panel, and goes to both the supressor in Position XI and out to the low pressure switch on the A/C receiver/dryer forward of the radiator. From there, power goes to the ccompressor clutch.

Likely blower relay in your case. Note fuse # maybe different. I don't remember what year car I wrote this for. The path is still the same.


I have checked all the fuses that may correspond with those and any other issues all fuses intact aside from one that has some sort of short.

Thanks for any assistance or ideas

..

[stepson]

Headlights: If you can find someone to swap relays with, put your headlight relay in their car. Do not put their headlight relay into your car. Reason: If there is something with your car that is frying the relay, your friend's relay will not get zapped. By putting your relay in your friend's car, you will know if it is the relay or something else with your car.

AC/Heater blower: After you check fuses, check that the 2 wire connection (under the hood and under the flimsy plastic wiper motor cover) to the blower is connected to something. You can also connect a small amp battery charger to the connection to check the blower motor. From there, I would definitely move to relays.

Cigar lighter fuse: Fuse chart shows that the fuse is common with instrument lights. I would venture a guess that someone has wired the cigar lighter with the power connected to ground. It's pretty easy to remove those connections to the cigar lighter from the passenger side of the console. See if that doesn't cure your fuse issue on this circuit.

Passenger side window switch: trace the wire from the switch to the connector. Some new switches don't come with the multi-terminal connector attached. Check for the multi-terminal connector. If it does not have one, chances are it was just wired up wrong. If the multi-terminal connector is present, that should reduce the chances that it was wired up wrong. If this is the case, I've noticed that the newer switches sometimes seem to get "stuck" and can be unstuck by rapidly tapping on the "up" side and then the "down" side in a somewhat forceful manner with one finger. I know it shouldn't be this way, but I've noticed sometimes that it just works.

[MainePorsche]

^
John, excellent point about the headlight relay swapping. Your recommendation is prudent.
Doubt the OP will carry through. Have seen him as listed in the forum more than once without even a question or reply.

[Landseer]

First things first. Has the fuse panel been removed and cleaned up? If not, you have some uber-basic work to do. Remove, clean with dremel wire brush, install new VW/Porsche fuses. Do not use common Bus fuses, they don't fit. Post closeups of the panel before and after removal, you can tell a lot from the panel and the wire condition at each plug. Go to wiring diagrams (you have em, right?) or 928 specialists website for the 81 diagrams. Gotta do the panel refresh and clean the grounds before anything else to make the rest of your electrical troubleshooting worthwhile.

The headlight relay is pretty expensive; has a series of relays within. But its likely the cause as noted.

You need to understand and make the blower fan work reliably. Fuse 17, a blue 25 amp, protects the fan.

Relay XXI manages fan power and allows you to control with variable speed switch on the HVAC unit.
(next to last relay, top row, right side of your CEB panel)

Relay XXII manages fan power for defroster only (far right on your CEB panel board, top row)

Basically, the fan has two separate circuits that can operate it, which share the fuse.

If your fuse 17 is good and cleanly mounted, then you can jumper either of those relays for a second to determine if the fan itself works. Usually they do, but it might squeal or the whole plenum where it mounts might be full of mouse nests and debris. That's why, on reinvigorating a car like yours, I dive right into the fan remove / refresh / reseal before even trying the fan. Anyhow, if you are impatient, go ahead and see if it works with a jumper.

Further, replace both relays with new 53 versions from roger, $5 each.

The defrost should work automatically when the bottom slider is moved all the way right.

With both switches moved to the right a little bit, defroster circuit is off, but fan runs automatically on lowest setting with ignition on... even when selector knob is off. And you can choose different speeds with sliders moved. Its important that your fan is in good shape, lubricated and not blocked, otherwise it will drag and burn the fuse. That's why you should mechanically inspect and repair the fan, and lube it, and test it outside the car, and reseal so water doesn't leak into panel, first. Your choice how to roll. If you don't fix it mechanically first, at least snake a vac hose into plenum and a light and ensure any mouse houses are gone. The reason this is important is the resistor. Speed is controlled on the fan in this circuit by diverting power to a big old resistor in the plenum, accessible from engine compartment. Think "wires hot like a toaster" coils, which is what exactly it is. IIRC, slow speed means more coils glowing red, and exposed to mouse nests, on that resistor. I missed one on daughters car and it filled cockpit with smoke.

If your fan, once working, starts cycling off/on --- that resistor has a problem and has to be fixed or replaced. Just tuck that away for later.


Advice on looking inside center console is crucial. Notorious for mouse houses and chewed shorted wires. And bad stereo installs.

Its possible to troubleshoot the window a variety of ways, might just be a switch. Early switches can be easily dis/re assembled after cleanup.
Again, good advice given, can jumper the window at the 18 pin door plug, but lets save that for now.


Here's a thread that should help you with electrical / grounds work Ground Cleaning, 16V Euro Post #13 shows a panel...hopefully you are reading other detailed accounts of this type of stuff on rennlist or here.

Really like the fact you are saving this car. Good work.

[81headache]

thank you all for your very usefully advise and links I am truly getting an education this was my dads car and is a labor of love for me.

I connected pass window switch to drivers side connector swith works fine and rolls down drivers window. the window is first thing i wanna fix as its summer and a little warm for any passengers especially the wife.

I took some pics of some wires under dash that looks suspicious to but they all look foriegn to me

[81headache]

this is what i found

if i disconnect the wires from the bottom of cigar lighter and cap them should that solve problem of popping the fuse.

also the brown wire pictured seems to be coming from hvac unit

[stepson]

81,
Obviously someone has been under your console. The seatbelt chime relay is the relay hanging out there in the picture. It has a place to be mounted tucked up under the console.

Any brown wire should be a ground. If it were to have power on it, something would be amiss, so you should be able to ground that brown wire without causing any difficulties.

So do you have the connector that plugs into the yellow connector for the pssenger window or is it just singular plugs? Did you try unsticking the passenger window switch? You may have to press hard on the switch to make the connection.

[cal928]

for your cigarette lighter problem, I have an 78, and the schematic shows the S5 fuse for the cigarette lighter(s) is also shared by the lights on the clock and goes thru the instrument light potentiometer under the dash. that could be a source of your problem, as a quick check go the the CE panel and unplug wire B8 this is the branch circuit that goes to the clock......F3 is the circuit that goes to the cigarette lighter(s).....at least on a 78.

[81headache]

there are three very similiar conectors a red for driver window a green which i asume is passenger window due to match green conector from switch and yellow for which i am not sure what its for

[Landseer]

Well, you have sunroof and window connectors.
The switches might be easily repairable by snapping apart and cleaning the points inside with 400 grit sandpaper.
Console doesn't look bad, but you need to do a more thorough job giving us camera angles. Where's the panel? where's the base of the lighter/ashtray, etc. More is better when it comes to pix.

Admirable save / effort, 100% behind you, wiring diagrams for your year are crucial. Yes, you will need to learn to read them, but its easy.


I used some wires harvested from a 944 harness to make better patches. Don't need to make them factory resto, just need to clean up the damage and sort it out. Good work, keep going.

[lfausty]

quick note/thought to headlight going up and not back down. if don't work then info above...relay...all that jazz.
when you turn the switch full on for them to come up go to front and palm/push the whole buckets/both towards you so they hit the stops. they may not have extended all the way so the relay(has several jobs) isn't switching to retract yet. or listen when you turn them on youll hear the light bar to stoppers hit and also the relay youll hear click . ???? ball of grds clean at pass light, connections under hlight motor, and gears(under rubber boot/on rotating bar that run em up/down gunked up....

[curtisr]

The 928 fuse panel is the source of all of this lousy shade-tree mechanic's woes and greatest joys. But, I'll never surrender.

[81headache]

good news got the passenger window working actually tested everything right through to the motor which i thought was the problem but was in good working order turned out to be gearbox that the motor spins was bound up and rusty inside popped the cover off with screw driver and cleaned out with staring fluid resealed with gasket goop and bit of macguyver tape added some diff lube from my rc cars and it works great with no money spent and a few hours with a buddy all in all a great day.

wanted to share my victory and maybe offer a solution to others with window problems

[Alan in AZ]

A few notes:

If you swap headlight relays - note that pre-S4 and S4 are entirely different (as are the motors). so make sure its of the same type.

I think your headlight issue is probably not the relay - and is likely a blown diode in the motor parkling mechanism (good news - much cheaper to fix with a diode from Radio Shack ...)

Check all your upper interior lights by removing them from the roof/hatch and inspecting for broken connectors (a classic failure).

Alan