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99 suburban 7.4 liter ECM wiring diagram

Im trying to find wiring diagram for my 99 suburban. I need to verifiy a few pins on the ECM are recieving power. I recently replaced the fuel pump but still not getting power from ecm to tell it to kick on. I have jumper across the relay and pump kicks on just fine with around 60 psi of pressure as soon as i remover the jumper wire pump kicks off. I order new a new ECM and having it programmed today at the dealership put i think its more of a wiring related issue and I would like to do further testing to verify before the dealership cost me my next born child.

Posted by JD John on

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5 Related Answers

darin brown

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SOURCE: Fuel pump relay or emergency engine shut off

something is killing the relays poss fuel pump drawing to much amperage check pump with amp probe is pump noisey?

Posted on Dec 19, 2008

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colin white

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SOURCE: 1998 Audi A4 1.8T fuel pump does not turn on

if you have diagnostic equipment you will be able to see the signal through serial data(if you believe it)the cranksensor is located near the rear of the engine pointing towards the radiator i think it goes to a grey plug....

Posted on Jan 05, 2009

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soporific

  • 1 Answer

SOURCE: My 1994 suburban engine stops. No fuel, no MIL light.

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

66 chrgr

mike loshbough

  • 1011 Answers

SOURCE: no voltage going to new fuel pump

The GRAY wire i believe going to the fuel pump is the hot wire it should come on for 2 seconds with just the key in the on position this is were you should check voltage for 2 seconds then it will go away until you crank the truck.Your oil sending unit is behind your distributor that could be the cause .

Posted on Aug 01, 2009

Jameel Bacchus

  • 105 Answers

SOURCE: need wiring diagram for 1991 honda accord to trace

email me at
[email protected]
for wiring diagram
I will send it for u

Posted on Sep 24, 2009

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Why wont 99 Chevrolet suburban start?


ok if the truck went through water some water may have got on the distributor wires i dont think its a fuel pump problem but if you could check to see if its firing at the spark plugs the check the fuel pressure and if you have some wd/40 spray the spark plug wires and the distributor cap and try starting the truck

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99 chevy s10 replaced fuel pump but the new one is not getting power i ran a hot wire to the pump and it comes on in the tank so i know the pump works.i replaced the relay under the hood that said fuel...


It sounds like you are on the right track. Here are the basics for your pump. I took a guess at the engine size and went with a 4.3 V6, Hopefully that is it.

1. There is an ECM B fuse, 20amp that feeds one side of the relay.
2. You have already mentioned the relay. The other side of the relay feeds from the VCM or Vehicle control module.

Remove your relay and check pin #3.. You should have 12volts with key on. If not check the ECM B fuse.
If you cross pin#3 and #5 on at the relay location you should feed 12 volts to your pump and it should run. If it does not, look for a ground problem on the black pump wire or a broken wire between the relay and the pump. I show a gray power wire to the pump.

Hope this helps.. Best of Luck..

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If you tell me your year model and engine, I may be able to find the wiring diagram for additional troubleshooting.

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It helps if you tell what year,model, engine you are working on. Is power at the Inertia Switch? The power comes from the FUEL PUMP RELAY, the ECM only grounds the relay to turn it on. but not knowing what you are working on, thats all the info I have .

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Look in the fuse box under the hood. Find fuse "ECM B" which is on circuit 120 which excites the fuel pump relay. This is the fuse you want to inspect. The relay pin next to it is controlled by the PCM. The other 2 pins on the relay control the pump and the other the prime circuit.

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My 1994 suburban engine stops. No fuel, no MIL light.


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.

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