Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Hi this is MATT CAREY, what model chevy do you have? That way I can look up the correct diagrams. I just had an Astro that would blow the ECM B fuse. Separated all the circuits with in line fuses one at a time. It would still blow the main ECM B fuse. then I added the last in line fuses, which were to the EVAP vent solenoid and one right after the fuel pump relay. ( I had already installed a fuse back at the tank, right before the fuel pump). Anyway, Couldn't get anything to blow. She is driving it now, waiting to see what blows?
Let me know your model ( pick up, suburban, etc.,.?) . And I can help. thanks, MATT
Check for pinched wires at the throttle body, or hanging on the exhaust.
Okay, I'll look up the correct diagram, and see what I can do to help.
The Reason for the wires near the throttle, is because ( at least on the Astro) the ECM is powered by that fuse, and the ECM controls the Injectors, ETC....
Do you already have a diagram, or would that help you. I'm gonna look now and see what I can find. MATT
Okay, I just checked it out. I would add an in line fuse on each leg coming right out of the fuse box. Then you can figure out which leg to search. You are correct, the fuse sends power to the fuel pump relay, the oil press. sw., and two legs to the ECM. Adding the the fuses in line to ECM will help figure if it is ecm related or not.
Where did you add your in line fuel pump fuse? MATT
Yes and No , you should focus on the orange wires, (with one exception, the tan/white power wire from the relay to the pump , and oil sw. to pump.) Put in line fuses in the orange wire right after the fuse box . What you did was good to eliminate the fuel pump, but not the original wiring to it. The original wiring could be rubbed and touching ground along the way to the fuel pump.
I did some research, for your year and model, and it seems that in almost every case, the problem was that the harness to the oil pressure sw. was rubbing/ shorting on the exhaust, heat shield, or bell housing. Doesn't mean that is your problem, but it's the best place to look. Good luck, MATT.
Sounds like reverse might be tweaking the motor to the side causing the short??
I'll be back tomorrow night.
I've been there, sometimes after digging into the harness , the short is gone. Good that it is not blowing fuses, but it would be nice to know where the problem was.
For you battery problem, is your alternator charging? How old are the batteries? Do you have a meter to check the ALt. , I assume you do. Let me know, if I can help. Check the charging voltage, if good, and the batteries are good,you might need to check for draw. Do the batteries die overnight? MATT
Ok, all problems appear to be fixed. In regards XXXXX XXXXX battery problem. I put in a brand new 800 amp battery and brand new 105 amp alternator. P/O had the dead battery warrantied so I got the new one for only $20 and with my Autozone reward card I got the $140 alternator for only $100!!!! Smokin deal. However, put those new items in and same problem. Next day found that my multi-battery isolator has a signal or "excitation" wire that leads from the fuse panel and provides 12 volt power to start the battery isolator. That wire was unplugged from the fuse panel. Plugged it back in and started it up and it roared a pretty sound and was running between 13.75 volts and 14.2 after warming up. Gonna keep the alternator even though old one was probably working but on last leg. Five years old and in 115 weather not gonna last long.
Spent a total of 5 hours re-taping and then putting new plastic on wire harness. That was a pain in the ass. I isolated the ECMB power lines with the in-line fuses still in them and secured that circuit separately from the main wire harness. Gonna leave it that way for about a month or so and see how it does. So far nothing will pop and I can do burn outs in reverse without any problem.
Thank you for all your help and your original answer suggesting the in-line fuses appears to be working great! Thank you so much!!
need help on a 1999 Chevy K3500 pickup with a 7.4 L