2008 Chevrolet Malibu Classic 3.5L
2008 Chevrolet Malibu (Classic) 160k
Had the following codes
-P0102 - Mass Air Flow Circuit Signal Low -P0128 - Coolant Thermostat -P0446 - Evap Vent Control Problem -P0455 - Evap System Leak (Large) -P0496 - Evap System Flow During Non-Purge -P0523 - Engine Oil Pressure Sensor Circuit Signal High
Also the AC did not work
Replaced the following
-Thermostat -MAF -Oil Pressure Sensor -Valve,Evap Purge Solenoid -Solenoid,Evap Emission Canister -Oil Change
Replaced all the parts and still getting P0102 - Mass Air Flow Circuit Signal Low.
Pin A - 5 Volt reference Pin B - has 12 volts, Pin C - has ground Pin D - is a signal wire and that's 1.8 volts Pin E - I'm just getting straight ground from the PCM. I've tested the harness to the PCM to the MAF sensor and it's good for that circuit. When you disconnect the ECU PIN E loses ground.
The original ECU had no AC and 1 MAF Code for P0102 then replaced the ECU with a used one and programmed it to the car and now the AC does work and has 2 MAF Sensor codes P0102 (Mass Air Flow Circuit Signal Low) and P0101 (Mass or Volume Air Flow Sensor A Circuit Range/Performance). I figured maybe the used one I got was bad so I got another Used one and it's throwing the exact same codes. If I put the old one back in the AC doesn't work and then just throws only the P0102 code. When using the 2 used ECUS it runs roughly and can keep it running by 2 footing it. I'm a little lost on what to do next.
Does anyone have any ideas?
Perform a load test on the power and ground circuits for the PCM is what he is asking you. I have had several of these types of vehicles that had a leaking electronic thermostat and the coolant wicked up into the wire harness. A couple came from other shops that had installed used PCMs a few times, they never noticed the corroded connector pins at the PCM. One was bad enough to have engine…
Are the replacement ECUS the same service number as the original ECU, and when programing them are you doing a replace and program or just a reprogram. Replace and program you need to correct the vin to get the correct calibration file, re -program will just use the vin in the used ecu and load the calibration file for that vin. Hope this helps Don
Did a replace and program. Apparently there are many different vehicles that use the same ECU. The 1st Used ECU came from a 2008 Chevrolet Equinox and the 2nd Used ECU came from a 2008 Chevrolet Impala.
It sounds like you have a wiring issue. I would throw a scope or graphing multimeter on the 5 volt reference and start wiggling wires. I have seen a ton of wiring issues on these.
The connector on the wire harness side could be needing replacement ? Have you got a frequency generator to simulate the signal to verify the ECM sees the correct Hz?
… The P0128 will deprive the owner of A/C and put the temp gauge on max cold(just to get them to bring it in for a check up)… just clearing the code will restore both the A/C functionality and the gauge operation… The other stuff will need some checking… I'd put a stat in it and do a little more testing on the other concerns. … Dan H. … Hobbs … South texas …
The MAF should have B+ on the Pnk/Blk, chassis ground on the Blk/Wht, and signal on the yellow, which is measured in Hz. What does the scanner say about G/sec., and/or Hz? Not reading at all, and all the signals are good? You're still at the PCM and/or the wiring. Check all signals at the ECM, not just at the sensor. The Tan/Blk is the ground for the IAT and has nothing to do with the MAF issue.
Ended up being the MAF sensor.. I replaced it twice 1 with a used oem and one with a new after market one and then got another used oem and fixed it..
This post shows why testing is important. You made a lot more work for yourself and others here than if you would have taken the time to test the parts.