ECM problem

Tiny
EDGAR ARMENTA
  • MEMBER
  • 2001 DODGE RAM
  • 5.2L
  • V8
  • RWD
  • AUTOMATIC
  • 187,000 MILES
I have a truck that has a bad ECM, I want to go buy another one but the problem is that there is no computer number on the truck, so I am not sure what the serial for the computer is. Is there any possible way to get this number without the computer? Because I cannot even get into it with a scanner I have, so I cannot get into the trucks information, and I need the number to be able to get another one, thanks.
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Tuesday, November 29th, 2016 AT 6:42 PM

8 Replies

Tiny
SATURNTECH9
  • EXPERT
There should be a part number on the computer itself have you looked there yet?
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Tuesday, November 29th, 2016 AT 6:56 PM
Tiny
SATURNTECH9
  • EXPERT
Also usually you can just get a computer by application.
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Tuesday, November 29th, 2016 AT 6:57 PM
Tiny
EDGAR ARMENTA
  • MEMBER
There is nothing on the computer itself, I mistyped. I am not sure if their is a number on the truck or not, just that there is nothing on the computer.
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Wednesday, November 30th, 2016 AT 11:08 AM
Tiny
SATURNTECH9
  • EXPERT
The dealer could use the VIN number to help find the correct computer. Otherwise look on rock auto dot com by application they should have one on there.
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Wednesday, November 30th, 2016 AT 12:51 PM
Tiny
EDGAR ARMENTA
  • MEMBER
Could I call them and ask? I got into the website and couldn't seem to find the computer, I searched in every possible category and it isn't there.
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Monday, December 26th, 2016 AT 11:20 AM
Tiny
CARADIODOC
  • EXPERT
Excuse me for butting in. Saturntech9 is right. You're making this way too difficult. Visit any salvage yard and ask for a computer for a 2001 truck with a 318 c.I. And automatic transmission. Since your old one doesn't have a sticker, it most likely was a rebuilt unit that had a rebuilder's sticker taped on, and that fell off. The part number on that paper would be different than the original number anyway.

These computers have an extremely low failure rate. You never listed the problem you're trying to solve. About 90 percent of the time when people don't do that, it turns out to not be a computer problem.
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Monday, December 26th, 2016 AT 11:33 AM
Tiny
EDGAR ARMENTA
  • MEMBER
I've already gone to a salvage yard and bought multiple computers where they indicate it's for this engine and trans, but no they don't work, on the original the gas pump doesn't work and I can't use a scanner to get into the system, I put in another computer and the pump works, but then the injectors don't get any pulse, and still can't get any communication with the ecm. If it wasn't the computer the pump wouldnt work on either of the two computers, and it would be the obd fuse that isn't working but the fuses are all good, triple checked them all, under hood and inside, I just want to find out the computer number that's all.
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Tuesday, December 27th, 2016 AT 1:32 PM
Tiny
CARADIODOC
  • EXPERT
I'm not following your logic, but I get the feeling you're looking in the wrong direction. You haven't mentioned anything about spark. Too many people get hung up on the first thing they find missing, which for some reason seems to be the fuel pump, then they waste their time and money in that system. You also have to check for spark. The hardest thing to check for quickly is injector pulses so we don't look at that.

If you've already gone through multiple computers, at some point it should dawn on you that isn't the cause of the problem. The best place to start is by checking if the automatic shutdown, (ASD) relay is turning on. Look for the wire that is the same color at every injector and at the ignition coil. On cars that is dark green / orange. I'm not sure if it's that color on the trucks. Probe that with a test light. You can also probe either of the smaller terminals on the back of the alternator if that is easier. Digital voltmeters usually don't respond fast enough for this.

You should see the test light light up for one second when you turn on the ignition switch. If it does, the ASD circuit is working and the computer has control of it. You should also hear the fuel pump hum for that one second. What is important is that relay must turn on again during engine rotation, (cranking or running). If it does not, suspect a failed crankshaft position sensor or camshaft position sensor.

If the ASD relay never turns on, suspect a problem in one of the 12 volt feed circuits to the Engine Computer. That can also cause a loss of communication with the scanner. Typically there are four 12 volt feeds, but that fourth one shows up from the ASD relay to verify it turned on when the computer requested it to. There should be one feed wire that has 12 volts all the time, and one that has 12 volts only when the ignition switch is on. There's a third one that is used mainly for the voltage regulator. I can't remember where it comes from, but I think the engine would still run if that one is missing.

If you need help with the wire colors or terminal numbers, one of us will dig up a wiring diagram and find them for you.
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Tuesday, December 27th, 2016 AT 3:40 PM

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