Bad Computer

Tiny
ERIC5735
  • MEMBER
  • 2002 MITSUBISHI DIAMANTE
  • 3.5L
  • V6
  • FWD
  • AUTOMATIC
  • 171,000 MILES
I have a bad computer can I buy a used computer from an 100 percent positive eBay used parts and get a mechanic to install it and program the used computer because of the transponder on key? Or do I need to go out and buy a new computer for mechanic to install?
Wednesday, March 29th, 2017 AT 10:51 PM

8 Replies

Tiny
STEVE W.
  • MECHANIC
  • 15,234 POSTS
What makes you think the ECM is bad?

As for the part. Talk to the shop you plan to use about it. Some will not use a "used" ECM because it is way to easy for it to be bad. Others do not have a problem but wont offer any type of warranty. Be sure that they can program it as well. Some vehicle makes can only be programmed by a dealer when it is a security item like the key.
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Thursday, March 30th, 2017 AT 1:18 AM
Tiny
ERIC5735
  • MEMBER
  • 6 POSTS
Had car Diagnose by electrians told me computer is no good and my vent solenoid needs to be replaced and to fix problem mechanic said labor plus parts would be 890 to fix
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Thursday, March 30th, 2017 AT 12:44 PM
Tiny
STEVE W.
  • MECHANIC
  • 15,234 POSTS
OK Vent solenoid would be for an EVAP leak. I take it the check engine light came on!

What is your car doing/not doing. I'd hate to see you replace the ECM if it's something like a bad ignition switch or bad transponder antenna or similar.
Not saying the mechanic is wrong, just don't like seeing people spend money for the wrong part.
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Thursday, March 30th, 2017 AT 2:48 PM
Tiny
ERIC5735
  • MEMBER
  • 6 POSTS
Yes check engine light is on car is hesitating during idle and while I drive I have an ob2 Bluetooth reader it said I had misfire on cylinder 3 that's what I original took it in for they told me computer is bad and I need to replace vent solenoid
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Monday, April 3rd, 2017 AT 3:49 PM
Tiny
ERIC5735
  • MEMBER
  • 6 POSTS
Car turns on normally just a little hesitant, gears shift okay, car doesnt rev like it should hesitant
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Monday, April 3rd, 2017 AT 4:03 PM
Tiny
STEVE W.
  • MECHANIC
  • 15,234 POSTS
Vent solenoid isn't that bad to change. Misfires can be caused by many things, plugs, bad wires, cap/rotor, bad injector, bad wire to the injector.

Easy to test the signal that turns on the injector. You need a simple test light called a noid light. Unplug the injector plug in the noid light and start the engine.
If the light is flashing the ECM is probably OK and the issue is with the injector or the ignition on that cylinder.
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Monday, April 3rd, 2017 AT 9:49 PM
Tiny
ERIC5735
  • MEMBER
  • 6 POSTS
Mechanic did noid light test on injectors already, misfire apparently are being cause by bad computer
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Friday, April 7th, 2017 AT 9:18 AM
Tiny
STEVE W.
  • MECHANIC
  • 15,234 POSTS
In that case you need an ECM. You don't have to buy a new one, you just need to reset the security features to match your vehicles system.

Just be sure that the part numbers are the same.
MR578512 if you don't have traction control.
MR578513 if you do

You might want to check your heater core. There are notes about ECM failure because of the core leaking and getting to the connectors and inside the unit.
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Friday, April 7th, 2017 AT 8:51 PM

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