98 S10 ECM I fuse blowing

98 S10 P/U with the 2.2, auto and no AC ("bean can" said the insurance man) with 80K. The fuel pump went out, so I got a new one from NAPA and swapped it in. After a week, it blew the ECM I fuse out of the blue in the middle of a left turn. Found and changed the fuse; next day I went a couple of blocks and it went out in the middle of another left turn. After a few days of this, it started blowing the fuse when I turned the key to START. I've swapped the fuel relay - it clicks when I turn the key to ON, but I don't hear the fuel pump - yeah, the radio's off :0)

Next, I'll see what kind of amperage is going across the fuse, but does this sound familiar to anyone? Am I looking at a new ECM?
Thanks

harryevan

ECM -1 fuse feeds ign module and coil and injector circuits aand VCM and crank shaft sensor..
You need to seperate the circuits and see which one is shorted.

A good wiring diagram will aid you in finding the circiuits.

Good Luck

Unplug the 2 pin connector at the ignition module and see if the fuse blows. If it doesn't the module may be bad if it does check the pink wire for a short to ground somwhere between the fuse, the computer, and the module.

Okay, it blows the fuse when I pull the two-wire connector from the ignition module. The pink wire IS shorted to ground.

Pulling the fuse, there is 12V on both sides of the fuse socket with the key off (actually out of the ignition). With the key turned to "ON", I get 6.2vdc on one side (the firewall side of the block) and 0v on the other side of the socket.

Unfortunately, I only have the diagram in the Haynes manual, which is just a little better than a block diagram. There's wire colors with a number - the pink wire has a 0.8 next to it, but there's no explanation in the manual whether that's voltage or amperage. Coudn't find a reference to the other wire at the ignition module (blue) but there was no short to ground there.

Just to see, I pulled the ECM B fuse, and it didn't have 12v on both sides, just one (the diagram said it was always hot).

The truck is in town, at my brother's, so I don't have easy access (I'd have to tow it 20 miles...) Is there a good source for a wiring diagram out there somewhere that's usable and doesn't cost an arm and a leg? Maybe with a reference as to which harness these wires are in?

Thanks Airjer_

harryevan

A friend said I should be looking at my grounds to be sure they are tight. Also, that if there's 12v on each side of the fuse while it's "OFF", but that drops in half when it goes to "ON", maybe it's the ignition switch?

I got a diagram from Autozone's site, but it doesn't really explain the other wire (blue) on the two-wire ignition module plug that I pulled to see if it blew the fuse on "START". The diagram shows the pink wire as one of 4, so I'm trying to figure out where that goes and if it has anything to do with this.

Thanks again

You pull the fuse out and you get 12 volts on both sides?

The ECM 1 fuse also feeds the PCM. Might be worth unplugging to see if it returns to normal.

The wire from the ignition switch (pink) splits. one goes the the ecm1 fuse the other feeds the gauges, SIR, and turn signal fuses. how does power look on those?

The red wire on the ignition switch is what supplies power to the pink wire throught the switch. how does the power look there?

i had the same problem i made left turn and the truck died i just put a new 2.2 in it as well ..... The problem was that the wireing harness the runs over the vaule cover and by the header. The plastic cover had got brittle and the wires started grounding out on the oil dip stick bracket by the header i relowcated it and bam it rums great.

And that was it. Thanks a bunch, it was shorting out on the manifold. Wrapped the harness in a piece of poly/kevlar conduit, which should be way beyond the protection it needs.

Working on this stuff, I always think it would be great if we could go back to when engineers bought, drove and worked on the cars they designed...