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windows, signals, brake lights...don't work

Hi All,

I suck at understanding electricity and am working hard to get caught up. I've done a search and haven't found any resolutions to my situation. I am slowly going through the process of diagnosing a no start on my S (that has sat for 6 years!). I would like to use the gauges to rule out ref sensor issues. Unfortunately, I have a HUGE electrical issue. I've been cleaning grounds (a few more to go) and replacing relays and fuses with no progress. From what I can tell, the following doesn't work:

Gauges, brake lights, windows, directional lights, warning buzzer

The following does work:

dome light, green "parking light" on the dash, gauge background lights, light under the hood

It sure feels like this must be related. Can anyone shed some light on a good place to dig into?

Thanks for any help!
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peter
1991 944S2 Cab, Crystal Silver Metallic "Platinum Banshee"
1987 944S Alpine White, Ice Shark Lights "Desert Ghost"
2015 Charger Rallye SXT
Old 02-21-2016, 08:50 AM
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So this is an 87/88 year car.

Check your battery voltage first. Is it above 12.5 volts? If not, charge the battery. Are the battery cables clean and tight? It could even be a bad battery that can't handle a load so it might be worth getting it tested.

With a good battery/connections, check all of the accessories to see what does / does not work. (lights, blower, horn, windows, dash, everything)

Check all of the fuses for blown or incorrect size, especially those of the non working items.

The next suspect would be the relays. A bad relay could affect one or more non working item.

There is a guide in the fuse box cover as to what the fuses and relays feed.

These would the most basic things to check. Good Luck!


A corodded wire connection such as the battery connections and grounds downstream could also be a cause. If this doesn't do it, then the switches (headlight and turn signal) .

Last edited by djnolan; 02-21-2016 at 09:58 AM..
Old 02-21-2016, 09:41 AM
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Hi DJ,

Thanks for the suggestions. I have some of the answers and then some questions.

This is an 87S. Battery is new and just off trickle charger for a full charge of 12.93 V. My headlight motor is disconnected (another unresolved problem) so the only strong load I can put on it is to try and start. Is cranks just fine and will even start with enough starter fluid. Is that enough of a load to confirm battery is good?

I scrubbed the battery cables and the connection for the negative cable to the body. I tested and replaced ALL fuses. I am still learning how to check relays but I've been switching them out with my S2 and haven't found any that don't work.

If I remember correctly, these issues began all at once. This smells like a wiring issue. Do you know how I can check power to the relay panel? Or, do you know where I would check for a wiring issue that could effect all these systems? I am going to go upside down and clean the driver foot well grounds. That leaves the one in the trunk and the one down low by the engine block.

Thanks again!
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peter
1991 944S2 Cab, Crystal Silver Metallic "Platinum Banshee"
1987 944S Alpine White, Ice Shark Lights "Desert Ghost"
2015 Charger Rallye SXT
Old 02-21-2016, 02:43 PM
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FWIW I learned that corrosion on the end of a wire can creep under the sleeve. I saw this on the brake fluid reservoir cap wires and the brake wear sensor wire harnesses. The copper wires were corroded, however other wires looked clean silver (galvanized)?

No idea this is relevant to you.
Old 02-21-2016, 02:53 PM
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Definitely go under the dash and check those grounds. They're not hard to reach if you take the seat out and lay in floor. Take the steering wheel off to.. LOTs more to get in and out.
Old 02-21-2016, 03:07 PM
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Every circuit in the car has a separate fuse, and many also have a separate relay so the best way to test the panel is to test the accessories.

If you try all of the accessories and report on what doesn't work maybe someone will see a pattern. Your list above was somewhat incomplete. Try every switch in the car, in the appropriate key position.

Hopefully it is simple and you don't end up having to tear the car apart.

Right now it seems centered in the drivers side and instrument cluster (there is a ground under the dash) but check and make sure everything else is working first.
Old 02-21-2016, 03:17 PM
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On 2nd thought check this first: There are 4 smaller brown wires on the main positive battery terminal and they each power different sets of accessories. Is it possible you left one disconnected or otherwise when you cleaned the battery terminals?

If you just cleaned the batter terminals this would make lot more sense than a ground or a bunch of fuses/relays all the sudden going bad...
Old 02-21-2016, 03:35 PM
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I agree with the suggestions already provided by others. From my own experience, when the battery was low, some things didn't work while others did (headlight motor wouldn't go down, sunroof wouldn't open). If your battery is new and reading 12.93 V then it should be ok, but if you have a spare battery it might not hurt to give it a try.

You mentioned that your engine almost runs on starter fluid. Have you tried re-installing the air cleaner, AFM, J-boot and all vacuum lines? I don't think that the engine will run without the entire intake circuit in place. Definitely mine won't run well if any of the vacuum lines aren't connected.

For the power windows, I had luck following Clark's Garage on cleaning the contacts and got mine working. The power for the passenger side switch flows through the driver's side switch, so both switches need to have clean contacts in order for both sides to work. Good luck!
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Old 02-21-2016, 05:41 PM
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Electric part of the ignition switch. Jiggle the key and see if the signals or one of the other malfunctioning components momentarily works.-Dave
Old 02-24-2016, 04:50 AM
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I just pulled the seats finally and have cleaned the four ground posts under the dash. As you know from above, I am not very knowledgeable about electronics so forgive the dumb question. With so many ways we can measure electronics, is there a way to measure my grounds? If I connected a digital multimeter to the ground and, somewhere else, couldn't I measure the resistance? Seems weird that this is always a guess if the grounds are bad or not.

Dave, thanks for the suggestion. This is the kind of thing that makes sense to me. I hope to try all of these later today.

Thanks!
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1991 944S2 Cab, Crystal Silver Metallic "Platinum Banshee"
1987 944S Alpine White, Ice Shark Lights "Desert Ghost"
2015 Charger Rallye SXT
Old 03-05-2016, 02:29 PM
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There's also grounds near the head lights. Also, did you clean the ground on the bell housing top? Additionally, under the fuse panel, there's 3 or 4 large connectors that normally are held in place by a large plastic slide. If you can't resolve this by other means, it's something, although somewhat unlikely, to be considered.
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Old 03-05-2016, 06:20 PM
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777 - you win another jackpot! My gauges, lights and windows work! I had forgotten about the grounds behind the headlight. There are about 6 brown wires attached there. They are a pain to get to because of a hard sensor that I couldn't remove. I was able to get my fingers in and rub sand paper on both sides of each loop and then sprayed a liberal amount of electronic cleaner. Back to the jiggling key guess, that makes my warning buzzer go on and off. I suspect that means my ignition switch is also going to be a problem.

Thanks again for the help!
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1991 944S2 Cab, Crystal Silver Metallic "Platinum Banshee"
1987 944S Alpine White, Ice Shark Lights "Desert Ghost"
2015 Charger Rallye SXT
Old 03-06-2016, 05:56 PM
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If wiggling the key makes the buzzer work, chances are the electrical part of the ignition witch is faulty. It is not that difficult of a job to replace it. Over the years I have seen this part fail fairly often and many times because the customer had a big heavy key fob or a heavy amount of keys hanging there.-Dave
Old 03-07-2016, 03:47 PM
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Actually the buzzer part of the ignition is a separate contact switch that is not part of the ignition switch that is located on the end of the lock barrel. There is a two pin connector (just to the left of the socket where the ignition switch fits in the picture) that connects to the ignition lock housing along the portion that houses the steering lock pin. That's the contact that makes the buzzer go off.


Last edited by dgcantrell; 03-07-2016 at 05:45 PM..
Old 03-07-2016, 05:40 PM
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Yeah, you're right. I was picturing the early 944 or 924s style switch but GostRidr appears to have late model stuff. That 911 style was never much problem.--Dave
Old 03-08-2016, 02:53 PM
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Hey DG and all,

I am revisiting this and have confirmed that my ignition needs to be replaced. Do you have a description of the two pin connector piece that is part of the warning buzzer so that I may replace that too? I will try and dig up a part number also.

Thanks!
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1991 944S2 Cab, Crystal Silver Metallic "Platinum Banshee"
1987 944S Alpine White, Ice Shark Lights "Desert Ghost"
2015 Charger Rallye SXT
Old 03-28-2016, 09:03 AM
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I think the two pin connector for the key buzzer is built into the ignition lock housing. it's pretty much sealed from what I can remember. it's simple contact switch that is actuated by the slider that engages/disengages the steering lock when you insert the key. I had inadvertently unplugged mine at some point moons ago (I guess when I removed the instrument panel to replace the odometer gear) and didn't realize it until I was experiencing DME relay issues and was checking the ignition switch and saw the connector was unplugged.
Old 03-28-2016, 09:41 AM
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