TEST / TROUBLE SHOOTING HELP GUIDE and REPAIR INFO by DJ Esco
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Note: Keep in mind sometimes the problem will re-occur immediately after repair is performed with Q31 or Q34s
I have dealt with may of these in my days.
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The most common are Q34 and Q31
Q34 controls the secondary runners
Q31 controls the evap solenoid
if Q34 is damaged be sure to check R77 by use of the tombstone method. keep in mind that on P28 and simular boards which normally do not control secondary runners these are damaged due to 12VDC being sent to a grounded output. you may want to consider using a relay depending on the vehicle application (year make model)
if Q31 then you may have a bad IAT sensor (melted) chack wiring purge plug may be connected instead of the intake temp sensor plug (common mistake)
I have done many repairs of these and even repaired attempted repairs done by other individuals, I dont mind helping anyone with this or other ECU related issues or questions, feel free to contact me anytime if you need.
DJ Esco
www.ecumods.com
(832)798-0000