Question about Cars & Trucks
No power going to my fuse block on half the block,,truck will not start and the ECM B, HORN/DM,1/CTSY. ALL FUSES ARE GOOD BUT THERE NO POWER GOING TO THEM AT ALL AND THE TRUCK WILL NOT START NO LIGHTS NO DOM LIGHTS NO FUEL PUMP WORKING AND NO FEED TO THE ELECTRONIC CONTROL MODULEBAT. FEED 10AMP IS GOOD STILL NOT GETTING POWER TO THAT PART OF MY FUSE BLOCK..NEED TO DOWNLOAD A WIRING DIAGRAM FOR 1987 CHEVY SILVERADO 10 ( FREE IF PROVID..E-MAIL PHILWLEWIS1@CHARTER.NET
Sorry, I don't have good enough wiring diagram for your model year?
Check for battery junction block, under the hood, one of the positive battery cables should go to it, see if there is a bunch of fusible links, check them. Use a testlight on out put side of link, check for voltage. If there is a handful of links, sorry, I don't know which one. Maybe you will get lucky and the first one you check will be the faulty one, where applicable. I don't usually get that lucky. If you make a hole in wire insulation, use finger nail polish or something to cover the holes.
I thought about using jumper wire for B+ to ecm B fuse for testing. I don't want to suggest anything that might cause you more problems, you need to fix it properly.
Posted on Jun 09, 2017
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Posted on Jan 02, 2017
I checked all of the fuseable links and they were all good. Next I decided to check all the power wires to the ECM and also the grounds from a wiring diagram because the Mil is controlled by the ecm and the bulb was good. The ecm is located behind the glove box. Bingo, the orange wire was only reading 3-5 volts at the ECM, but 12.5 volts after the fuseable link at the underhood fuse block (passenger side firewall). I ran a temp wire directly from after the fuseable link to the orange wire at the ecm and the ecm turned back on and the Mil or "check engine soon" light came on too. The truck started up and has never run smoother.
Note that at first the truck just stalled out and I could restart it right away with no error codes. Eventually the stalling became more frequent with longer reset times required. Once it threw a "code 54" and I thought it was fuel related as each time the gas stopped and I could still start the truck with gas poured into the TB. Ignition ok. My fuel pump turned on and ran if I tested it. I even checked the pressure regulator and the fuel filter to no avail.The orange wire that powers up the ecm is technically part or the fuel pump relay circuit as it also feeds the fuel pump relay 12.5 volts all the time. The thin orange wire from the fuse block is joined to two other thin orange wires in the large group of wires that heads to the ecm along the firewall behind the engine. I had to dig it out of the many wires to find it and remove a lot of tape. It is amazing to me that this one little orange wire could cause so much grief and be so hard to track down. I could not have afforded to take this problem to the Dealer.
Posted on Mar 26, 2009
Diagram should be on the inside of the fuse box or relay cluster lid/cover. If Test light has 1 wire and a sharp tip? Yes, but only if you push the horn button too ;-)
My guess is that the horn lost its ground, but you can check this with the light. The horn only beeps when both GROUND and Pos 12v are present. The horn button gives the relay 12v to close, and the relay gives the horn 12v to operate. The ground is always connected.
Connect tester clipwire to 12v source (battery, headlight (has to be on) and touch its tip to metal of car. Does it light? Good. the tester is working and the 12v is a good source.
Touch one of the 2 horn connection or wires (poke it thru the plastic - why tip is sharp). Does it light? Touch the other, does it?
If both light, (1 will be brighter) we can assume the horn coil is good and it is getting a good ground and I was wrong (it happens... but not often). The side that is BRIGHTER is the ground wire side.
Now have someone mash the horn button. Do you hear a tiny click? That is the horn relay. If not, look for the horn relay fuse and replace it. If you DID hear the click, the relay coil is good and is trying to switch 12v to drive the horn.
Now is time to locate and replace the horn fuse or the relay may have bad contacts. Look at the other relay part numbers in the cluster and see if there is a match for the horn one. Swap it out and try the horn.
Hope this all helps. To 'test' the horn, touch the dim side again anf listen for a scratching sound. That is the 12v going thru the tiny bulb in the tester (a resistance) and trying to drive the horn.
Posted on Mar 27, 2009
That eliminates the crankshaft and camshaft position sensors. Have you checked the fuel injector itself for an open winding or stuck valve plunger? There should not be a steady 12 volts to the injector--if good injector, it would be spraying fuel steadily into the throttle body. But at least the engine should try to run if poorly. Take the injector out, dry it off with air, and intermittently apply 12 volts to one terminal while grounding the other. You should hear a click from inside every time you touch 12 volts. If not, replace it. If it does, it may be plugged with debris. Try blowing through it in reverse with compressed air.
Posted on Jul 17, 2009
you don't have enough pressure in your system. odds are you have a leak someplace and the factory installed a saftey switch to keep the ac from running when there is no pressure. This way you don't end up burning up your compressor.
Posted on Jan 13, 2010
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next page go to the bottom an click on I agree ! Next page click on wiring diagrams an enter your vehicle info. System - Electrical distribution . Subsystem - Fuse panel . Here you go Jerry hope this helps you !
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