Cougar

The wiring in the doorjamb can get damaged internally.

Had some response to the request for info. One poster suggested looking for some fuses under the glove box area. Another said to check the fusible links.

Thanks for the reply Ratty2Austin. I couldn't remember exactly how the problem occured. I still suspect a noisey alternator could be the problem, with this one at least. One us has the right solution for the problem I think.

Thanks for the replies fellas. We will look for the fuses and link, though the fuse for the charging lamp circuit is the only one that has a low voltage problem. The simpified way this circuit works for the '88 model GL is; power is supplied through fuse #12 and passes on through to the warning lights. It then goes through fuse #9 and then to the L terminal on the alternator. The power excites the alternator field to create the output for the battery. There is a break somewhere in the wiring between the supply power and the warning light so the exciter is not getting any voltage. NorthWet: Since you have a diagram can you tell me exactly where the wire path goes after it gets past the warning light?

Yes that's right. If things are ok I would suspect the AC volts on the output lead of the alternator would be less than about .2 volts. If things are not right then you would see more. Check to see what the AC voltage is at idle and then around 2,500 RPM. Let me know what you get for readings.

Does anyone have a good diagram of the charging circuit for a Brat? The fuse that ties to the L lead of the alternator has no voltage on it. The lead that appears to be damaged may be black, we need to know how it ties to power.

Looking at my manual again it shows that not only the charge light is in the circuit but other warning lights tie in also. As our next step, lets make sure all the warning lights turn on when the ignition is on. If they are ok, then lets verify you can get charging going by jumpering one of the working 15a fuse circuits to the charge fuse. The alternator should charge then. Another thing you might try is tapping on suspected areas with a screwdriver handle to see for you can pinpoint the area that way. We sure could use a good wiring diagram about now. I will try making a new post to see if anyone can help out with this. That is one fat cat in the picture. I feel sorry for it. It can't be good for it to be so heavy.

You should get a test light probe and verify that power is not getting to the relay. The relay could have power to it and still not let power pass if the contacts inside are bad. This is a common problem with relays. If you don't have a probe they are cheap to get at a auto store, Sears, or just about any retail store with an auto section.

It sounds like you found it and don't know how to test it. Is that right?

They should be able to ohm out which wires go to what by comparing the two switches in each position.

I would have the fuel pressure checked. My guess is you have a weak pump.

I seem to recall from other posts that if the bearings are bad then the alignment for the pickup inside the disty gets to be a problem. I am only going by what I seem to recall and I may not be remembering correctly. If the disty was replaced not to long ago then I would have to say then that either the tach is at fault or there is noise at the lower RPM's and........ FLASH (mind flash that is). Wait a minute. Maybe there is noise from the alternator at lower RPM's causing this to happen. Perhaps some of the output diodes are bad. The more I think about this the more I think that is what is going on. Forget the disty, check the alternator for noise. If you have a digital voltmeter put it on the AC mode and see if the noise goes down as the RPM's go up.

Technicians are standing by!

There may be an air pocket problem. I have heard filling the system through the top radiator hose helps get rid of the air.

Well it appears there are some differences then. "my wiring diagram shows a wire leaving the charge light and going straight to a 15A fuse" Does the diagram show where the other side of the fuse goes? The power side of it. "What is the #12 fuse called?" The fuse supplies power to many control circuits for relays and warning lights. One thing you might try is to check the voltage of all the fuses and see if you can find any more with less than 12 volts on them with the car running or the ignition on at least.

Well you both should check the power to the compressor. There is a relay and fuse mounted on the right hand strut tower. There may be a problem with the relay.

I think this may mean the disty bearings may be bad.

Your statement about the coolant resevoir filling up makes me think you may have a head gasket leak sorry to say. I would have a block check done at a shop to verify that. To is cheap to do.

I think you are on the right track Boo. I would try replacing the pump. It's a fairly common failure item.

Is your 'charge fuse' fuse number 9? Just curious to know if it is the same number as mine is. The 5 volts you saw is probably being backfed from the alternator. That wire appears to be ok. It is the wiring between fuse #12, through the lamp and to fuse #9 that may be the problem. The exciter power is supposed to come from fuse #12, through the charge lamp, then through fuse #9, and then to the alternators' WR wire. At least if your wiring is the same as my manual shows it to be for an '88 model GL.

I thought I would check my '88 manual to see how things are wired and it looks close or the same as yours. The WR wire from the alternator goes to fuse #9 and then becomes a Brown wire going to the 'Charge' warning light. On the other side of the light connection the wire becomes a Blk/White wire that ties to a connector and then becomes a Red/Yellow wire that ties to fuse #12. Your problem may be with the wire between fuse #12 (if yours is the same) and the charge lamp.

You both may be having trouble with the vent doors. They are controlled by vacuum and there may be a leak that is causing a problem. Especially if the problem happens while driving fast, making the throttle open more and creating less vacuum.

You could try to find some Infinitys that will fit. I think you would like those and they aren't overly priced.

Checking for voltage at various points while the problem is happening should be able to lead you to the problem fairly quick.

Good call NorthWet.