My 1992 Chevy Blazer is blowing the fuse for the instrument panel as soon as you put a new one in. sometimes it will not blow for a day or two. Thanks when this happens the alt will not charge .

 

Did anyone install any stereo equipment or electronics recently? LED gauges, fog lights, tachs? Just curious. A dead short should be easy enough to find. One thing that might work is if you put a 12V test light on the circuit (the light will be BRIGHT!). As you watch the light, one by one, systematically pull fuses (put them back if the light stays bright). When you pull a fuse that dims that test light considerably, you have found the offending circuit which will help you locate it more quickly. Schematics are good but common sense used with schematics will often lead to an easier or at least quicker solution.

So... has anyone installed any gizmos? If so, what was installed?

Thanks and good luck!

A.

 

no nothing new . I did pull the radio out and looked anyways and i also did the test light there is no draw . i spent 2 hrs moving wires under dash and under hood when it was running and i cant get it to blow but after i drive it for a bit it will blow and keep blowing then

 

How could a circuit that blows a fuse show no draw? If it's only while driving then it must be intermittent. Those shorts can be a bit of a punk to fix.

Good luck.
A.

 

Hi, I do not know how to start a new post so I am just replying on this one. I have a very similar situation with my 92 blazer, except it is my ign/gauge fuse, it keeps blowing every time i put a new one in. I know that means it is a short, and I did put a new car stereo in, but that was over a year ago. Is there a way for me to find it without paying a mechanic tons of money in labor to? Let me know, Thanks

 

to directly quote my other thread....

"This sounds like the IGN/GAU fuse. This fuse controls the alternator charging, o2 sensor, transmission (with fuse blown, it forces 3rd gear. Awful for starting from a stop and high revs at highway speed), gauge lights, and the warning buzz for the key being in. This fuse used to blow on me every time I took it wheeling, got very frustrating.

Start by checking the fuse. it's a 20-amp located in the fuse box in the driver's side footwell and it is labeled IGN/GAU. After you replace the fuse or verify it is good, you need to start looking for the short.

My short (which is also the most common) was as the wiring harness leading to the trans goes between the firewall and the transmission. If you look down directly past the distributor, towards the underside of the car, you should see a big loomed harness running to the underside of the car, which is most likely pinched between the trans/firewall and causing your problem.

If you verify a pinched harness in there (even just a little bit), start by unplugging the o2 sensor, the large connector that goes into the transmission on the passenger side, and the small connector that goes into the transmission on the driver's side. Then you can pull some (but not all) of the harness back towards the top of the motor, which should net you enough room to see if there is any bare copper. The wire that is vital to the systems you are talking about is PINK/BLACK, but I found 17 bare/shorted wires when I got my harness visible.

Easiest way to repair is to get as much harness up from underneath the car (the large connector for the trans wouldn't fit between the trans/firewall for me. If you jack the trans maybe you could get it through, but you'll see it won't yield much help. Next, under the glove box inside the car you'll find where the harness comes into the car and to the ECU. Unplug it from the ECU and feed the harness/plug through the firewall into the engine bay. Next you can take the harness/plug and pull it up and over the exhaust manifolds, again moving towards the distributor. This will be as far as you can get the wiring, but should put the pinched wiring at about hood height, at the distributor. Now you can lean over the motor (or sit on the motor if your 130lbs soaking wet like I am) and start repairing your wire.

Re-install in the reverse order, and be sure to use a few zip ties to keep the harness towards the passenger side of the car where it goes between the trans/firewall. You'll see that as you go towards the passenger side, the gap gets bigger for the wiring harness. By keeping it towards that side, you should be clear of this problem forever.

Feel free to PM me if you have any questions. I wish I had pictures from my repair.... "