1992 Caprice wagon fuse 6 issue

I recently did a lot of work to my wagon (92 caprice, 5.7L) It's been sitting for 6-8 months. I rebuilt the suspension and replaced the core support. When I got ready to take it to the shop for an alignment, I discovered fuse 6 was blown.

The fuse is marked "GEN" on the panel. The manual shows it to be Alternator, Daytime Running Lights, and Heater/A/C.

Everytime I turn the key to "on" the fuse blows. I've tried it with the blower motor disconnected, the alternator disconnected (both power from battery and plug), blower motor switch disconnected, a/c power switch disconnected, a/c disconnected, all fuses except those needed to start disconnected as well as combinations of the above. I've also tried with the various related relays disconnected.

I'm stumped. I can start it and run on the battery only. The only electrical stuff I worked on when repairing it was the airbag sensors. I replaced the entire front suspension and steering, so I did have the switch on the power steering hose disconnected, as well as the battery disconnected for the entirety. I also had the door panels off and put new speakers in the front doors. It also throws code 22, the Vehicle Speed Sensor-speedo does not work.

Anyone have any ideas? #6 is the only one that blows. Thanks.

Sounds like its a pinched power cable grounding out.

If you leave the fuse out, and check the low side of the fuse socket to ground, then start unplugging things you worked on, you should find one of them that is shorting to ground. I believe #6 goes to the AC control module as well. Since you worked on it, anything you replaced or modified is suspect, even the wiring to that part. Check anywhere the wire passes through a metal panel. It could even be two wires pinched together. But foremost of all, check everywhere you did anything, even down to the individual wire.

I trapped a wire under a plastic piece, and it took about 2 months to work its way to the nearby bolt, and shorted the entire lighting system, and blew the fuse. It took me a while to find it, because I had forgotten that I had removed and replaced the part months before.

Damn showoff Fred has to say it in a fancier way than I!LOL

I are a college gradgiate, I knows the fancy way to say dem tings.

Fred Kiehl wrote:

I are a college gradgiate, I knows the fancy way to say dem tings.

Boy did yu get your muney's worf out of dem teachings!

I found the short.

The alternator wires go from the fuse panel to the a/c, then past the blower motor, and through the firewall on the passenger side. It then travels to the front of the engine and under the oil pan. Just above the oil pan, it splits and drops off wires for some sensors and continues up to the alt.

My alt wires were broken in the loom just above where it dropped the sensor wires. My best guess is that I rested or scraped the power steering pump on it when changing it out. Spliced in some wires and put on a new plug, good to go.

Now to sort out my idle problem.

Thanks for the help.

I also learned a neat trick: Use a flasher to test the fuse. When it's shorted, you can hear the flasher blinking. When the flasher stops making noise, you've found it. It was a little easier than trying to see the light..

Nice catch Floormonkey. Glad you found the issue. Happier that you posted up as to what you found , and how you found it. It might help the next guy out down the road.


Dave


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floormonkey wrote:

I found the short.  

The alternator wires go from the fuse panel to the a/c, then past the blower motor, and through the firewall on the passenger side.  It then travels to the front of the engine and under the oil pan.  Just above the oil pan, it splits and drops off wires for some sensors and continues up to the alt.

My alt wires were broken in the loom just above where it dropped the sensor wires.  My best guess is that I rested or scraped the power steering pump on it when changing it out.  Spliced in some wires and put on a new plug, good to go.

Now to sort out my idle problem.  

Thanks for the help.

So what is your idle issue?

I tried several things to find the short.  What eventually worked was using my toner left over from my security/lv days, a fluke 3000 (http://www.amazon.com/Fluke-Networks-PRO3000-Tone-Probe/dp/B000FTADX0/ref=pd_sim_hi_2?ie=UTF8&refRID=0NTZFZ9CRK70R8M5BA0W)

That toner is probably a little $$ for the average diy, but this one should do the same, and is cheap enough to own: http://www.amazon.com/Sinometer-MS6812-Generator-Cable-Tracer/dp/B004YLXR24/ref=sr_1_9?s=industrial&ie=UTF8&qid=1402929513&sr=1-9&keywords=tone+and+probe

Hooked it up to the fuse panel.  You can then just touch the end of the toner to the wiring harness to see if the current is continuous or shorted.  I touched the end of the alternator plug and no tone, so I followed it back until I found tone.  When I pulled off the wire loom, it was obvious.  

The most frustrating thing was that I forgot I had the toner and spent a bunch of time trying to find the short.  Once I had the toner, it was less than 10 minutes before I had it pinpointed to a 2" region.

Fred-I fixed the idle.  It was a low idle at startup, then after about 10 seconds it would kick to a high idle.  When doing the test drive, it would die.  The MAF sensor was unplugged.  Now the idle is good.

Now I have a stumble/acceleration issue...I'm doing FF and injector cleaning today, hopefully it's simple.  These nickle and dimes are wearing me out.

Fuel filter fixed the stumble/acceleration problem. It's now inspected and street legal. I think I'm going to replace the master cylinder, the brakes are a little off and I've bled them well. The front reservoir doesn't seem to be "bubbling" when the pedal is depressed.

It goes to the alignment shop and a/c shop this week, by Monday I should be back rolling in the wagon.