Gen light / Charging problems.

[DaGlitch]

Ok to start off only Gen2 light comes on when the key is in run position, and the volt gauge is in between the red and yellow on the left (low volts) side of the gauge. I crank her over... She starts up, and Gen2 light stays on for a little bit longer, then proceeds to go out.

The problem. Gen1 light never comes on . I tested the alternator and was getting about .45v out of it with the engine running. Tested passenger side alternator and was seeing around 25v. I JUST got the driver side alternator fully rebuilt and put back on, but it seems to be pushing the same amount of voltage from it before the rebuild. I checked the ground it seemed to be fine, as well as the battery cable. the only thing i could think of was the plug that has the brown? and red wire on it that plugs into the alt. Is it possible a fusible link blew somewhere that would cause this? I checked the ones i could see near the driver-side firewall and they looked fine. Also, what is this little single brown plug with a rubber boot around it for? The TM doesn't even have anything extra hooked to alt1.

Any help is GREATLY appreciated!!! Tryin to get a daily driver up and runnin

Pic of some of the fusible links
http://getglitched.com/images/M1009/IMG_0290.JPG

 

[Ken_86gt]

I'm new to these trucks, but on other GM cars of that era if the alt or gen light does not come on when the key is on before starting, then the alt will not charge. Usually it is a bad bulb. Did you replace or test the bulb?

 

[DaGlitch]

even if it was a bad bulb, would that prevent it from charging?

 

[Ken_86gt]

Well I know on a Fiero this is definitely true. I would try the bulb.

 

[DaGlitch]

Interesting... Guess i'll give a bulb a shot. Gotta find me a part number for one

 

[Crash_AF]

From all of the information I have gathered yes, if the bulb is bad the alternator won't charge. Part number for the bulb is 194... same as the side marker lights.

You could try swapping the two alternators to see if it works in the Gen2 position to eliminate the alternator itself as the problem...

Later,
Joe

 

[DaGlitch]

swapped bulbs from Gen2 and no bueno, still doesn't light up. Will try swapping the alternators in a few, n will let ya'll know how it goes.

 

[lavarok]

The single brown wire is depicted on E-11 of the 34 TM. It is part of the diagnostic wiring. I believe the STE-ICE used this for RPM readings.

Rather than rely on a visual check of the fusible link. Use your electrical meter to verify continuity. Looks can be deceiving.

 

[DaGlitch]

Rather than rely on a visual check of the fusible link. Use your electrical meter to verify continuity. Looks can be deceiving.

Actually i already did this and got continuity where i needed it. Thanks for the info on that little brown wire

 

[Crash_AF]

There is one other possibly easy fix for the problem... the Bosch relay under the dash might have gone bad. It controls the Gen 2 system and if it's bad, nothing works.

Under the dash directly beneath the factory stereo opening is a bracket holding three relays, the big silver relay is the starter relay, the two smaller ones are the voltmeter and Gen2 relays. They are standard Bosch relays used in all sorts of automotive applications. Swap the two smaller black cube relays and see if your gen2 light comes on. If so, then the relay was bad. If the Voltmeter doesn't work, that would confirm it. If it does work, then it was just a bad connection.

If you have to pick up a new relay, most automotive stores carry them as fog light relays and such. I just ask for an A/C relay for a 1988 Jeep Cherokee since most parts monkeys behind the counter don't know what a 'Bosch Relay' is...

Later,
Joe

 

[NPD732]

Check the contacts of the bulb socket. The least bit of corossion on the brass contacts will cause the bulb not to light. Make sure the socket makes good contact with the plastic membrane circuit board and the copper on it is clean. These membrane circuit boards and sockets are a big pain and I have had to troubleshoot every CUCV I have bought.

 

[2mtrucks]

Is there a Bosch relay for gen 1?

 

[doghead]

no there is not

 

[DaGlitch]

Check the contacts of the bulb socket. The least bit of corossion on the brass contacts will cause the bulb not to light. Make sure the socket makes good contact with the plastic membrane circuit board and the copper on it is clean. These membrane circuit boards and sockets are a big pain and I have had to troubleshoot every CUCV I have bought.

Well well well... Took a screw driver to the contacts on the cluster membrane and scraped them off and started workin again . looked like some kind of build up from battery acid or something. Thanks for all the help guys!!! Now i just gotta figure out the transmission problem. I'll make another thread about it after i have gone over a few things i saw suggested around these forums.

 

[319]

Check the contacts of the bulb socket. The least bit of corossion on the brass contacts will cause the bulb not to light. Make sure the socket makes good contact with the plastic membrane circuit board and the copper on it is clean. These membrane circuit boards and sockets are a big pain and I have had to troubleshoot every CUCV I have bought.

I use a pencil eraser on the circuit board contacts and a real fine fingernail file/board on the brass lamp socket contacts. After all of the contacts are cleaned you'll find the lamps are brighter too!

 

[CUCV85]

Well well well... Took a screw driver to the contacts on the cluster membrane and scraped them off and started workin again . looked like some kind of build up from battery acid or something. Thanks for all the help guys!!! Now i just gotta figure out the transmission problem. I'll make another thread about it after i have gone over a few things i saw suggested around these forums.

Transmission problem Hmmm well check your vacuum lines and the modulator in the side of the transmission. I had the hard line going down to transmission crack, replaced all lines with soft hose for 6.00 and modulator was 11.99 md-48 advance auto parts. There's a screw in the modulator turn to adjust shift points, also rock back the vacuume regulator valve toward the cab. It's on the injection pump throttle shaft.

 

[DaGlitch]

Yea thanks for the info. Figured out the transmission problem as well. Turned out the governor was sticking quite badly. So I spent like 20 bucks for a new one, and works like a charm. Thanks for the info though

 

[Mudstone]

i think i'm having this same problem but i don't understand the steps to troubleshoot it... or to fix it. My gen1 light isn't coming on anymore... my heater is finicky i have to wiggle stuff to get it to turn on. my voltmeter was showing green is now in high yellow. I have no multimeter. and electronics scare/baffle me. if someone could idiot proof this... would be very helpful. Truck is also having a **** of a time starting first thing in the morn when cold. I ordered new wellman 070's. Better yet anyone wanna come help me out with this on sunday... i can give you gas money, beverage of choice and a homecooked meal? lol well any info would be great.

 

[DaGlitch]

I have no multimeter. and electronics scare/baffle me. if someone could idiot proof this... would be very helpful.

I'm gonna try to get out this weekend and do some write ups for both Gen1 and Gen2 charging problems (separate writeup for each). So stay tuned, and i'll try to solve a lot of common problems like yours.

 

[jsrovers]

My truck does the same exact thing. I just leave the heater fan on the notch below high and dont see the light anymore. Dont you get cooked when its on high?
If it aint broke dont fix it.