Vehicle stalls and blows ECM fuse

KS CUSTOMS

MEMBER
1991 CHEVROLET S-10
4.3L
6 CYL
2WD
AUTOMATIC
240,000 MILES

I recently put a new transmission in my truck listed above a 700r4 because the factory one gave out. Ever since then I'll have the problem of when I put it in reverse the rear tires will try and spin and then the truck dies and blows the ECM fuse. Which I believe is the fuel pump and such. I replaced the fuse once and everything was fine and then it started doing it again. I think I put probably 6 fuses in it tonight over and over trying it and it kept popping them. I even tried a bigger size just to see. I didn't have this problem before. But I wouldn't think the transmission would have an effect on this? Or possibly it could. Thanks!

Monday, December 23rd, 2019 AT 10:49 PM

1 Reply

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello,

The fuse keeps blowing because you have a short to ground in the circuit that the fuse is protecting. This happens because of one of the laws of Ohm's law, the laws that govern electricity. This law states that if one of the three properties of electricity is constant[Voltage-Voltage is always constant in an automotive application, battery voltage] and one of the other two go down[Resistance-Resistance goes to zero when a short to ground happens as there is a direct path back to the battery's negative terminal] then the last property must go up proportionally[Amperage-Amperage/Current goes up to battery amperage]. The amperage surpasses the amperage rating of the fuse and "pop", the fuse blows protecting the component[s] in the circuit, just as it was designed to do. So, you need to find the short to ground, fix it, then replace the fuse. In the diagrams down below I have included the Power-train Management wiring diagrams and call outs and a guide explaining how to find sort to grounds in an automotive electrical circuit. You will need to use a Digital Multi Meter[DMM] to go through these guides, so here is a link below explaining how to use one below, if needed:

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Please go through these guides and get back to us with what you are able to find out.

Thanks,
Alex
2CarPros

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