Archived GEN Light

[EGILLILAND]

Really bummed here. Changing the oil before pulling the trailer to take the kids out dirt bikin'.



While "wiggling" a filter wrench in behind the oil filter I grounded out one of the hot leads on the back of the alternator (sparks etc. ).



Finished the oil change. Drove out only to notice the "GEN" light on and no charging (12Volts) on the in-dash volt-meter.



Guessing I fried some diode, a relay, worse the Generator, or worse of all the PCM.



Hoping that since I goofed this up during a fairly common task of changing the oil... one of you fellow TDR'ers have been down this road and might be able to help me expedite the troubleshooting. Might save the weekend for me and I would sure appreciate the help.



Off to AllData.com to start troubleshooting.



Thanks for any inputs.



Eric

 

[HBarlow]

My guess is you zapped one or more diodes in the alternator. A local Autozone or other auto part supplier may be able to test alternator output and prove it but you can probably do the same thing with a simple voltmeter. From hot charge line on the alternator to ground should read about 14 volts when the engine is running. If not, it's a safe bet to buy a rebuilt alternator from Autozone or other parts supplier.

 

[FourBarR]

Service Bulltin 08-23-00 install rubber boot on B+ terminal # 044871442. To prevent the problem you had.

 

[B.G. Smith]

Check the terminal on the alternator and see if it is still hot, (12 volts). If not then the only thing you hurt is the fusible link at the PDC. The diodes are between the winding and the out put terminal and ground and should not be affected. The little wire to the alternator comes from the PCM, again should not be affected. bg

 

[EGILLILAND]

Harvey and BG, thanks.

Found the 120A fuse blown in the power distribution center.

BG, from PDC do you mean "power distribution center"? Can't say I could point to the fusible link in the engine compartment. I know what it is, what they look like and what they do. Any pointers in the engine compartment on how to locate the fusible link?

Again thanks...

Eric

 

[B.G. Smith]

If you have a 120 amp fuse there may not be a fusible link. Yes it is in the power distribution center and would be right where the big cables enter/exit and is an uninsulated copper strip held in lace by two screws. bg

 

[B.G. Smith]

If you have a 120 amp fuse there may not be a fusible link. Yes it is in the power distribution center and would be right where the big cables enter/exit and is an uninsulated copper strip held in lace by two screws. bg

And yes, as FourBarR states above, by all means, cover that terminal with something to keep that from happening again, I just wrapped some duct tape around the terminal on the 99 I had after I lit it up the first time. bg. bl

 

[EGILLILAND]

Still have 12V on the back of the alternator. But no 12V on the alternator side of the 120A fuse in the power distro center.
This is looking like a "fusible link" yes?

 

[EGILLILAND]

Ahh... starting to see now. Put the laptop on the workbench.



yup... there appears to be a 120A fuse vice a fusible link. Going to start chasing the wire run from the back of the alternator to the PDC now.

 

[B.G. Smith]

I don't have a good schematic of the wiring on a 97. What I have shows the wire to be a #6 wire, black with a grey stripe. It should be the only wire on the altenator that is hot with the ign. switch off. Yeah, I would trace out the wire and check the connections where it ties into the PDC and the alternator. bg

 

[GAmes]

My 97 has 4 fusable links from the drivers side battery. Easy to ID. One color at the terminal, a shrink wrap and another color coming out. I think the one you are looking for is black going into a red/ black stripe wire.

 

[EGILLILAND]

New info. With the engine running there was 34V on the back hot lead of the alternator. Pretty sure it was the 120A fuse in the PDC.

Went to NAPA, brought back an assortment of fuses.

The alternator works again. Just the fuse. I guess I should count myself lucky.
Thanks to everyone for jumping in to save a weekend.
Hope someone else can benefit from this.
Eric

 

[Dieselnut59]

Wise choice to deal with NAPA. Autozone is JUNK. Fuses, bulbs, oil may be ok form there but their alternators, water pumps and starters SUCK!