Electrical nightmare... Yes I've searched and tried
 

About 3 days ago my turn signals quit working, I didn't think much of it. Driving basically only to and from work. Then yesterday on a long haul
Back from getting some parts the instrument cluster gauges (besides gas) all shit down. The lights still on just the gauges didn't work. Now the PFC is only reading 10.5-11.3 on batt V.
I just swapped alternators about 3 weeks ago. I have checked most the connections I can think of and can't seem to find any sort of short or corrosion or anything anywhere. I have also looked through the wiring diagram. Figure this isn't the first time it's happened to an FD so I'm turning to you.

Also, the gauges did decide to work again randomly a few times on the ride home, and after the bat-v dropped it also decided to start charging at 13.5-14v

Checked the starter connections just incase, cleaned them. New battery terminals. Cleaned alternator connections, cleaned the grounds that I could find. Checked front and rear lights for wiring issues. Still Nothing. Not used to an alternator just kind of working. All I've ever seen is alive or dead so my mind is set in some sort of short but I guess maybe it could just be the alternator

Low voltage causes heaps of weird things.
Whats the voltage at the battery with the car running?

It should be about 14.5v if your alternator is working.

If you don't have a multi-meter then you can disconnect the negative battery terminal while the car is running. The car should stay running if the alternator is working. Car will shut off if its not working.

Maybe this unit (CPU #2)? It runs the directional signals... and some other stuff.

Heres an update.

I installed a brand new high output alternator from IRP. New plug\pigtail. Removed the battery harness and stripped it down, replaced any corroded grounds, cleaned and re-wrapped it. Also put in a new starter (battery is relocated so the positive is daisy chained from tge alt, to the starter, then to the battery. Removed and cleaned every ground i could possibly find, and cleaned every plug under the hood out.

The problem repeats itself in the same fashion as such

Start car, its running at 11.5ish. This is at the alternator, battery and PFC. If i give it gas up to 2500 or so RPM the voltage will jump to 14-14.1 again read at multiple points. Once it starts to get warm the voltage will start to dwindle, little by little until its just below 12.

Regardless of letting it rev up and stay at 2500+ rpm it will not jump back up.

My only thought now is something down the line is not triggerimg the alternator to charge. For some reason none of the manuals download for me. What is each of the 2 wires in the plug for, and where are they routed to? Input is greatly appreciated. Everythjng sounds just fine even at thw low voltaage and everything seems to work besides the signals or emergency flashers. Chasimg my tail here

I was reading all over and seen multiple posts about one of those wires running through the cluster? And I've seen a bunch of mixed answers on what that cpu#2 does or controls. Additionally I determined the dash lights and gauges were from a loose pin in the fuseblock. And simply pressing lightly on the fuse they will power on. The turn signals click but just no lights.

Usually if i have problems like that the alternator and battery go hand in hand. If one goes bad seems the other isnt far behind. Dont know if thats it but if you have done all the other whats a battery hurt.

cpu#2 does affect the signals, it's still a suspect. Did you check all your fuses? Try cleaning your terminals and such, too.

Do you have an underdrive alternator pulley? Some of them are very aggressive and will significantly drop voltage at idle.

It is normal for voltage to be higher when cold and lower when hot, that's part of how the alternator works. I usually see 14v cold and 13.5 warm, which is totally cool.

Dale

Also battery harness or left side engine harness maybe old and not allowing good electrical flow

One wire is from the regulator to battery voltage and one wire is the turn on wire for the charge warning lamp. Here is the troubleshooting section G

http://www.rotaryheads.com/PDF/3rd_g...l%20System.pdf



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Fix the cluster issue you are having and check that the "S" terminal sees battery voltage at the connector on the alternator.

It has an SR motorsports under drive, I am switching battery's and back to stock pulley to eliminate those possibilities. The car starts and remains at 12.5v I took the dash out last night and will be inspecting all of the connections and fuse boxes. The original owner came to help me and mentioned the dash lights/gauges once upon a time were finicky. Which is something that I also encountered. I have clear access to cpu #2 now and I'll look at and replace that if need be. Whatever the 2 black/blue wires coming off of the ignition cylinder are for, the 1 looks iffy. Also the light for the key input stays on.

After speaking with IRP I have made the decision the yellowtop, the under drive could be the cause but I am taking the time to inspect other things.

I was going to run a direct line from the battery to the alternator terminal to see if the issue is in that wire and wherever it's routed. I know it goes somewhere along or into the drivers fuse box. I would think of it was messed up though it would be over charging not under charging. Thanks for all the help, I will check everything you guys have mentioned. Keep the suggestions coming ����

The S terminal (green/white) sees 12.5. Same as the output of the alternator

From this website:

Note that field current through the charge light controls the voltage regulator in the alternator. Read down in the article to see what happens if the charge light is burned out (especially if there is no resistor in parallel with it... namely the alternator won't work at all).

^ cool, I was looking for that info and couldn't find it.

Try a new battery

Sounds like your cluster is dying as well. My speedo and tach stopped work, would randomly work. Then odometer went out as well.

So if the cluster is messed up its extremely likely the car just won't charge...

Tore a ton of stuff apart. Inspecting a lot of things, dissected the kick panel fuse box and found a couple of loose female spade connectors. Replaced them and broke every fingernail to get things back together. The turn signals now work, and the gauges now work (besides the lights since the dimmer is disconnected. The only lights I can get to light up are the brake light, and the high beam light. I'm going to have a buddy lend me both cpu#2 and a cluster to test each out. Alternator is out to be inspected also. I'll post back with more. Additionally the car doesn't seem to want to do that "click" no start bs anymore. Yes... It ran without an alt.
About the same as it did with one. Wish me luck I'm needing things to start coming together on this for me.

CPU #2 unplugged. Issue still exists with other known working alternator. Checking continuity of the wires and everything is good up into the cabin. Figuring out the ignition switch now (or trying) and the interlock. I checked the voltage and terminal s has 12.5v with the car off? I'm not sure if that's correct. It doesn't change when the car is running or on acc.

Swapped out the cluster with a friends. Odometer works now; battery light works now. Using an older alternator. Car fired out and was at 13.5v, started stumbling.. And then died. And now won't fire. This car has kid of always struggled from a cold dead start. Making progress at least. Perfume at thing is my friend drove his car without a cluster at all for a few weeks without issue... Anyways. Wish me luck. Will update when I have actual answers.

Okay... For reference I am 99% sure it was the instrument cluster. It quit running because I somehow went through 7 gallons of gas troubleshooting it and vehicles don't run without gas. It's basically fixed. Besides the headlights won't pop up, the cluster won't illuminate, and the tail lights won't turn on for running lights. Use the KISS method... Make sure the bulb works before you tear everything apart... Thanks for your help everyone

Got everything sorted now? Headlights tailights etc.

Nope... Headlights, and brake lights work. But the front left corner and parking light are the only lights from the daytime running that turn on.
The right side, tail and instrument cluster all don't turn on. Tracing wires tomorrow. Not sure if the CPU #2 would do that, or if it would do all or nothing... I inspected it and it looked great.

Got it... Only thing I haven't tested is the cluster lights.

It was the wire going from the drivers side harness to the passenger side corner light and parking light. Once it got current everything else came on too. It's daisy chained around the car. Like old Christmas lights... I'll update when I test the car under load.