ClassicStyle

Hello RennFriends, I've run into an issue that has sufficiently stumped me, and I'm not sure where to go to even search for a solution at this point, so I thought I'd start here.

My 85/2 944 NA won't turn on. Not "won't start", not "won't turn over", but simply no power reaches the car from the battery. A few quick diagnosis points I've already tested:

• The battery is good. Get 12.54v out of it at the terminals.
• Power is reaching the fuse panel (12.48v to be precise)
• Battery-to-chassis ground is good
• No blown fuses
• The car WAS running till I flashed the high beams, at which point the ENTIRE car went dark and engine died
• No "magic smoke" was let out of any part of the vehicle
• Dash, buzzers, starters, none of it turns on now

Truly, I'm lost.

I'm pretty good with electrical problems, but this has me stumped. I figure I shorted to ground somewhere along the high-beam circuit, however none of the headlight circuits have blown fuses. I also don't smell the tell-tale odor of having smoked a wire or components, that I assume would have come along with shorting a 12v wire on a 7.5A circuit to ground. I find it difficult to believe a wire in any circuit within the driver's compartment could have fried without smoking and smelling the whole place to high heaven.

Is there an in-line fuse (or circuit breaker) I should be aware of between fuse panel and ignition or some other wire?

Help me Rennbi wan kenobi, you're my only hope!

ClassicStyle

So, let me take a stab at answering my own question with a few logic statements...

IF the fuse panel is getting power,
AND the ignition relay pin 30 is getting power
THEN the problem must occur after the fuse panel but before any electrical component

IF Ignition switch pin 30 is getting power
BUT nothing else is getting power,
THEN it stands to reason there is a problem with the ignition switch

HOWEVER things that are not (or at least I believe should not be) dependent on ignition switch function are still not operating. For instance, the under-hood courtesy light does not show voltage on it with the hood up (granted, I just did this test and it's 2 AM - I don't know even if the hood ajar switch is working, let alone present).

Headlights are another circuit that do not rely on ignition switch function and are not currently working.

Can anyone validate my statements for logical accuracy (or fallacy)?

mel_t_vin

Have never experience this failure.

Do your running lights turn on with the head light switch at position 1? Can you turn your interior courtesy lights on? Does your door ajar chime ring with key in/ignition on?

ClassicStyle

Thank you for the reply!!!

To answer your questions in order; No, they do not. No, I can not. No it does not (but that's a bit of a red herring because my door jamb switches are busted to the "door is always closed" position).

Strangely, this evening I was out ripping my dash apart to get to the back of the ignition switch thinking that might be the cause. I disconnected the following in order to reach it:

• Instrument Cluster
• Horn button/steering wheel
• Turn indicator switch arm
• Windshield wiper switch arm
• Cruise Control arm
• Headlight switch
• Dash light dimmer ****
• Fog light switch

I noticed there is a little two-pin plug attached to the ignition switch (can someone tell me what this plug's purpose is?), and the connection comes undone rather easily. After removing the main plug connector from the back of the ignition switch, inspecting it, and reconnecting it, I noticed the 2-pin connection came loose. I plugged that back in, turned the key on, and the car came to life!!!

[EDIT]One thing I just remembered. I disconnected the 4-pin white plastic connector on the headlight actuator motor prior to the car coming back to life. I wonder if this is some sort of high-drain condition in the headlight motor? [END EDIT]

Until I blipped the high beam switch again in the reassembly process, at which point the ENTIRE car went dark. Not a single electrical component on the car works. Again.

Gotta say, I'm incredibly lost and frustrated at this point. I've put about 7 hours into this issue now and made zero progress.

mel_t_vin

Do not think the cluster needs to be removed to access the ignition switch.

Not sure, but that two-prong connector could be the power lead to the switch itself. What color are the two wires?

Re: the flasher stalk causing problems...is any of the wiring harness [e.g. two-prong leads] in proximity of the mechanical operation of the flasher, whereby pulling the stalk dislodges the wires?

marc abrams

You have power going to the fuse box, does any of the fuses have power?

ClassicStyle

@Allen: It may not have, but it came out easily, so it's out.

The two prong connector is a female plug that goes onto the ignition housing, it has a red and green wire.

Unfortunately none of the harness is interfering with mechanical operation of the stalk.

@Marc: The fuse box has power, and I have power going through all the fuses. The fuse tester that sits in one of the relay sockets is also functioning properly. I have no clue if that's a factory fuse tester, but it's there and I tried it.

I'm going to start trying to trace wires through the harness for continuity and the short to ground this evening, but that's a long and slow process. I appreciate the continued support from ya'll, and I'm open to retrying ideas I've already done.

marc abrams

Okay, with a incandescent bulb type test light and the headlights and ignition switch both switched on, place the ground lead of the test light on the engine and a few inches away from the battery terminal probe each one of the positive wires from the battery. If all good, check power at the fuse box connector "C" pin number 22 and 42, connector "E" pin number 25 and 31, connector "21" pin number 21. All should be hot.

ClassicStyle

All right, I'll be home in 2 hours and will give that a try first. Thank you, Marc!

mel_t_vin

Going out on a limb...power to the switch [red] and signal to the starter solenoid [green]?

Was hoping Marc would chime in...he's the resident electrical/wiring diagram guru. You're in good hands...

ClassicStyle

Marc, Allen, thank you both!

During the probing process of the battery cables, following Marc's procedure, the smaller red primaries running to the fuse panel sparked, and the vehicle began working again.

Upon closer inspection, the wires had corroded to the point of failure, and probing them with the test light flexed them enough to re-connect the flow of power.

It seems like such an obvious thing, but by the fact I was getting voltage at the fuse panel, I was extremely confused. Learned something new today.

Again, thank you both for responding to my pleas! I re-assembled the positive wires coming off the battery positive post with a new clamp, and voila, everything works.

Now I'm off to find a thread on why the headlamp motor stops half-way in the raised position. I'm assuming a spot on the brushes is failing to contact...

Cheers,
Randall

mel_t_vin

Well done, Randall. It appears the power leads are as important as the ground leads...poor, broken, or corroded connections will wreak all kinds of havoc.

Re: improper headlight operation...if memory serves, that could be an indication of a failing motor-mounted relay.

ClassicStyle

Thanks for the lead, Allen. I'll check it out!

marc abrams

Randall, glad you found your problem.

Allen, thank you for the kind words.

mel_t_vin

Randall, don't remember if you said how long you've had your 944. Are you currently looking for any parts/spares/cores?