I am having an issue with a 1997 T/A popping PCM IGN fuses. The car has longtubes, ory, catback, CAI, converter, and a mail order tune. It started after after a high speed WOT run and the car died. Following that it would blow them every couple minutes, now as soon as you turn the key.

I have pulled the pcm and checked the connections and wiring and everything looks in place. check wires around the trans and everything looks in place there as well. i did find some exposed wires going to the ICM so I corrected that and the problem persist, plus according to my wiring diagram those are not on the same circuit. From what I can see on my wiring diagram the only things on the circuit are the pcm and the trans and the owners manual shows pcm, trans, and evap system. I unpluged the evap valve and solenoid and the issue is still there.

Any assistance would be great.

Thanks

 

I had a 92 Blazer that drove me nuts until I took my power probe home & found the issue It was on the bottom side of the harness the lil metal rubber coated hanger cut threw a few wires chucked the holder & repaired 3 wires & it was good The power probe saved more headache Just unplug the circuit untill the buzzer stops then trace back on the harness Best 120 bucks I ever spent on that tool

 

You can use a test light and do the same thing. Just solder two wires on a medium sized bulb, something like a tail light, and clip it between the battery and the battery cable. (After you remove it of course) Or clip it across the blown fuse. Then start looking for the problem. I use a clip lead, just cut it in half and solder the bulb in. Then you already have a clip at each end.

Is the fuse it's blowing the 10 amp fuse?

Al 95 Z28

 

correct, the 10 amp PCM IGN fuse

it seems to be related to how much heat is in the engine or how long you have been driving. this morning it idled for about 30 minutes, drove for about 10, idled again for about 15, and drove again and popped on the second drive. i brought extra fuses in case it popped in the middle of the road somewhere, which of course it did. only this time i popped the extra fuses as soon as i turned the key. towed it back and didnt feel like messing with it so i let it sit. later this afternoon it didnt pop on the key turn and fired up fine.

 

That fuse goes to 2 pins on the pcm and to the transmission. Once inside the trans it powers all the solenoids. Could be one of the solenoids shorting when hot. Time to track down the draw with a meter. The solenoids are tcc pwm 10-15 ohms .8-1.2amps, tcc 21-33 ohms .36-.57 amps, 1-2 & 2-3 19-31 ohms .38-.63amps, 3-2 20-32 ohms .37-.60 amps.

 

good info, thanks.

I did this test this morning and unfortunately i do not think my problem is here. tested the resistance for the solenoids at the plug and all were within spec. tested them again at the pcm terminals to ensure i have good wire continuity and got matching results. plugged everything back together with a new fuse and fired it up and it popped it within a few minutes of idling. put another fuse in and it popped on key turn so i know the issue was active. tested all the resistances again and all were found to be within spec.

also not sure if this is any assistance, i turned the key with each of the 4 pcm terminals unplugged individually as well as with the pcm out of the car and the fuse still pops on the key turn.

the saga continues. . .

 

That fuse also goes to the EGR vacuum solenoid, not EVAP like you said in your first post.

 

I used to have a light bulb soldered to a blown fuse lol but with the power pro you can get neck deep in the engine bay & not worry about a burn spot Done that a couple of times on seadoo seats & it sucks when you gotta pay for a customers seat cover at 100 a pop I knew someone on here would chime in with Fbody specific info Thats why this site rocks

 

If it blows with the trans unplugged and the pcm unplugged then the wire is touching ground somewhere. Start tracing the wire. That fuse only powers other things in V6 cars.

 

When you get desperate, split the wires up and put three 5 amp fuses in. Then you'll know what circuit is blowing the fuse. Worked on a real nasty Datsun some years ago. Would randomly blow a fuse. After I split the circuit I found a defective choke warning light switch. (Had a manual choke with a reminder light in the dash.) I was about the fourth shop that worked on it. It would blow the fuse about once a month. I split the circuit and gave it back to the customer. She brought it back and told me it was fixed. I checked and found one blown fuse She didn't notice the lamp was out.

Al 95 Z28

 

I think I have found and repaired the issue. Turns out a wire on the harness for the 3-2 solenoid was intermittently grounding out on the valve body. repaired the wire and the issue has not presented itself again. hope this takes care of it

thanks for the info man, extremely helpful. if your ever in tallahassee hit me up and ill buy you a beer

 

Sounds like you got it! Most times finding the right info is half the battle. Glad to help out when I can.