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Dan, ASE Certified Technician
Category: Chevy
Satisfied Customers: 2270
Experience:  20 Year Factory Trained Current GM Technician
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Chevrolet Silverado 1500 Classic LS how do i reset the ecm

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how do i reset the ecm on a 2000 chevrolet 1500 silverado after i replaced it with a new one that has been flashed
My name is Dan.
What does the security light do when you try to start it?
Does the service engine soon light up when you turn the key on?
Customer: replied 5 years ago.
when i try to start it the security light goes off and the battery light stats on and the servics engine light comes on when i turn key on
will the engine crank/spin when try to start?

why did you replace the computer?
Customer: replied 5 years ago.
yes the engine spins when you try to start . i thought the fuel pump went out so changed the relay that didn t fix it so i changed the fuel pump because you couldn t hear the pump run when you turn key on so i thought the ecm wasn t sending a message to the pump
Ok can you hear the fuel pump run now after you changed the pump?

Have you checked the ECM B fuse under the hood?
Customer: replied 5 years ago.
no the fuel pump does not run . yes i have checked the ecm b fuse it is good
So there is no fuel getting up to the engine?
You checked the fuse and the relay?
Put your finger on the fuel pump relay and have someone turn the key on. You should be able to feel the relay kick on and then back off 2 seconds later. Can you feel/hear that?

Next thing is to check the power to the fuel pump, Do you have a volt meter or a test light and know how to do some tests?
Customer: replied 5 years ago.
the relay does kick on and off i checked that . yes i do have a volt meter and test light
We need to check the wires on top of the tank for power and ground. The big gray wire should have power and the big black wire is the ground wire. There should only be power for 2 seconds after the key is turned on unless the engine is cranking, then it has power while cranking and running.
Some of these trucks have a different connector to wire in when a fuel pump is replaced or on a recall. The splice where the new connector is wired in could be an issue.
Check these and let me know and we can go from there.
Customer: replied 5 years ago.
i had to splice a new plug in on to my truck harness i have checked the wires to make sure they are crimped good and all wires were color matched
Have you checked for power and ground back there?

If we are not getting fuel pressure up to the engine, and the relay clicks and the fuse is good, We need to find out if we are missing the power or the ground or if we have both power and ground, then the new fuel pump is bad.
Customer: replied 5 years ago.
how do i check to see if i have power or ground
Find a good ground on the truck to hook up the test light. May want to string a wire from the battery negative post and connect it to the test light. Unplug the connector on the fuel pump and touch the other end of the test light to the terminal of the gray wire on the fuel pump connector. Have someone turn the key on and the test light should come on for 2 seconds and then go off.
To test the ground wire, the big black wire, connect the test light clamp to the battery positive post and touch the terminal of the black wire with the test light and it should light up.
Check that and let me know.
Customer: replied 5 years ago.
i will have to get back with you tommorrow thanks
That is fine, Just post back here and it will let me know when you do and I will get back with you as soon as possible. I should be on tomorrow evening also to help you out.
Customer: replied 5 years ago.
Hey Dan are you on line
Customer: replied 5 years ago.

Hey Dan, i checked the power and ground wires. i have ground but no power. how do i get power to the pump

Ok there is a spot in the fuse box to check to see if power is going through the relay. Locate the fuel pump relay and then fuse 35, between the 2 spots there is a port( sometimes labeled 36) to test if the relay is sending power to the circuit. Test that for power while someone turns the key on.
It is a direct circuit from the pump to the fuse box. If you have power at the port in the fuse box but not at the fuel pump connector, check the splice where you connected the new connector end. If ok, you will have to start tracing wires. Sometime mice will get under the fuse box and chew wires.
Dan, ASE Certified Technician
Category: Chevy
Satisfied Customers: 2270
Experience: 20 Year Factory Trained Current GM Technician
Dan and 2 other Chevy Specialists are ready to help you
Customer: replied 5 years ago.
Hey Dan the port was hot so i checked the wires under the fuse panel under the hood they were ok, so i started tracing the wire all the way back and found a splice that someone had run to a switch under the dash. when they did this after they did not tape up the splice and it corroied and broke contact. Thanks to you and your vast amount of knowledge my truck is up and running Thanks again Charlie
Thanks for the accept Charlie,
Don't it feel good to find and fix a wiring issue like that?

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One thing to be aware of, If you replaced that computer, the new computer needs to have the crankshaft variation learned. I am not experienced with replacing a computer with a preprogrammed computer. The computers I get, I have to program myself. but the crankshaft sensor needs to be learned to the computer. I don't think there is a way to do it without being on the truck. May want to ask the auto part store that. You have to have a scan tool to do that procedure. If not, you can get false misfires showing up and cause drivability issues.

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