SureTrack Community Fix: Harsh HHR
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Diagnosing and repairing transmissions can be a complicated process. Sometimes you need a little help from your friends before diving in further. SureTrack community member Abe_Lincoln had a Chevrolet HHR that came in for harsh shifting and not going into overdrive. They posed their question to the community, and with the help of fellow community member dmckemie12 and others, they were able to resolve the issue quickly.
The following Community Fix summarizes the interaction between members of the community that led to the solution.
2008 Chevrolet HHR LT 2.4L
Harsh 2-3 transmission shift, replaced solenoid.
Vehicle will not shift into overdrive, 2-3 shift is harsh, p0977 appears in conjunction with p0700.
Diagnostic Steps Performed/Parts Replaced
Test drove vehicle. Plugged in scan tool (bi-directional). Using functional tests, observed live data displaying that 2-3 solenoid was commanded to operate. Disconnected transaxle wire harness, removed plastic clip that covers back side of connector for access to back-probing, plugged connector back in to transaxle. Using software data, proceeded to diagnose and back probe pin e (ign b+). Test light pigtailed to gnd confirms b+ at pin e (pink wire). Solenoid 2-3 is yel w/ blk, pin b. Test light between pin e and b confirms light off (normal). Used scan tool to command TCM 2-3 solenoid on, test light does not illuminate (not normal). Confirmed contact with back-probe connections. Still, no illumination. Checked gnd and control side of wiring for fault, all is good…no opens or shorts. OEM testing that I have done condemns TCM for diagnosis. If I’m wrong it’s 6.5 hrs labor in the tube for solenoid. For grins and giggles, I did an extra test. I ran test light pigtailed from b+ to known good solenoid 1-2 (pin a). Commanded scan tool to actuate, test light reads 12.4v solid. Did the same thing EXCEPT moved back-probe to pin b (2-3 solenoid), and this time after command, test light flickers as if the TCM is engaging a duty cycle only for that solenoid.
Is this normal for 2-3 solenoid circuit on this vehicle? 1-2 solenoid circuit reads 12+ volts, but 2-3 flickers with test light pigtailed to b+…..but then I have no test light illumination ONLY for 2-3 solenoid WHEN test light is placed between pin e (b+ ign) and pin b (2-3 sol).
Best Answer from Community Member dmckemie12
The 2-3 solenoid and circuit should do everything the exact same as the 1-2 solenoid and circuit. Both are either off or on, they are not PWM. Only other test you can do is to measure the resistance of both solenoids, should be 19-31 ohms. It sounds like you have covered most the bases and need a TCM.
Turns out the solenoid itself was fried. Since the solenoid was toast, my thought is that the TCM was continually attempting to send the signal to engage the solenoid. but since it was shorted out, the TCM kept sending the signal, at such a rapid pace, that looked like a PWM signal. Problem solved, the TCM is in good shape.
Replaced 2-3 solenoid in transmission. Test drove vehicle and it now shifts as it should and goes into overdrive.
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