HHR tranny woes

[Alex_V]

'06 HHR, 184K, 2.4L/auto. Initial behavior was hold 1st too long and shift hard into 2nd, then goes straight from 2nd to 4th - did it pretty much every time. P700? transmission communication DTC. First measure was to check and clean connections, so I unplugged the TCM (with the battery hooked up - maybe I knew better), no real surprises there, but upon hooking it back up, it won't crank. Zilch. Lights burn brightly while key is turned to "start", so it's not a bad connection - no click, no nothing. I suspect the neutral safety switch function is being impeded. Tried resetting with my Snap-on "brick" scanner, but no codes present. With everything hooked back up I unhooked the battery for 30+ minutes, no change.

What's next?

 

[CT8]

What did you mess with? Start there.

 

[WyrTwister]

Look for blown fuses , first .

 

[Alex_V]

It was the remains of a buy-here-pay-here shutdown transmitter. I apparently tugged on a wire that was the signal wire from the ignition switch to an ISO relay that was spliced into circuit to the starter solenoid. Cut that bugger out and it's good as new, but the transmission is still acting up - ran fine for a few minutes and a few shift cycles, now it's right back to high revving first, then straight from 2 to 4. I'm suspecting the TCM.

 

[Rand]

Originally Posted By: Alex_V
It was the remains of a buy-here-pay-here shutdown transmitter. I apparently tugged on a wire that was the signal wire from the ignition switch to an ISO relay that was spliced into circuit to the starter solenoid. Cut that bugger out and it's good as new, but the transmission is still acting up - ran fine for a few minutes and a few shift cycles, now it's right back to high revving first, then straight from 2 to 4. I'm suspecting the TCM.


I'd suspect internal transmission issue.. since it has that many miles.

TCM is possibly compensating for some transmission issue.

Does it have fresh transmission fluid in the correct amount?

 

[Oildudeny]

Sounds like a transmission safety lockout in the programming to prevent further damage.

 

[clinebarger]

P0700 is just a MIL request sent to the the ECM from the TCM as the ECM controls the MIL. It also means there IS a trouble code stored in the TCM.

Using a Snap-on MT2500 on a CAN "Control Area Network" vehicle is stretching the abilities of the tool, Though a version 7.1 & higher domestic software along with a CAN adapter should work on this vehicle.
If your using the global OBD on older software....It won't access the TCM.

The 4T45E is a pretty good unit, So I wouldn't condemn it just yet. T42 TCM's are very robust as well, I've only ran across 2 or 3 bad ones in my career.......Working at GM dealers, Rebuilding transmissions & doing LS swaps for most of it means I have quite a bit of experience with them.

 

[Leo99]

Originally Posted By: Alex_V
It was the remains of a buy-here-pay-here shutdown transmitter. I apparently tugged on a wire that was the signal wire from the ignition switch to an ISO relay that was spliced into circuit to the starter solenoid. Cut that bugger out and it's good as new, but the transmission is still acting up - ran fine for a few minutes and a few shift cycles, now it's right back to high revving first, then straight from 2 to 4. I'm suspecting the TCM.


I was going to guess some sort of security anti-theft device got tiggered. Never heard of a shutdown transmitter before.

If it's capable of running properly for a few minutes, maybe it's a computer/sensor thing and not a mechanical thing.

 

[Alex_V]

My scanner gives menu options for model years up to 2007, and was using domestic VIN entry mode. I was able to access the functional test for manual gear shifts and it did manipulate shifting... except when I went 2>3 on the scanner, it would go straight to 4th.

After getting it running it acted fine for 3-4 cycles, then went back to its antics. The owner said he'd observed the same behavior after unhooking the battery for a while, more than once. Seems like an electronic problem to me, too.

 

[clinebarger]

Is the ECM still setting a P0700?

 

[VinceVaughnce]

The top solenoid (1-2 shifter) could be heat damaged and can play havoc with the shift selection. The coils in the shift solenoid can overheat and degrade from being energized for too long, which causes a cascade effect- magnet wire loses it's varnish, windings short out, coil resistance drops, coil current skyrockets, increased current loads solenoid with more heat causing two subsequent failures: power transistor in TCM overheats, plastic solenoid body disintegrates/melts.

Of course the problem could be anything from line pressure solenoid (doubtful since it skips a gear) or the pressure switches, to debris but those are less likely than a roasted Shift Solenoid A.

Usually the TCM can detect if a solenoid is stuck open or closed via the pressure switches- check the TCM code. On our 4T45, the ECM/TCM is a shared unit, so I always got the trans codes with a regular scanner.

 

[clinebarger]

I considered solenoid electrical & mechanical concerns....As you said, The 4T40E/4T45E is notorious for solenoid burn-up.

The problem is....Each malfunctioning combination (Solenoid A stuck ON/Off or Solenoid B stuck ON/OFF) only gives TWO ratios.

The Pressure Switch combinations on GM 4 speeds ONLY provide Manual Valve position, Not Shift Valve position/Shift Solenoid state. The TCM will set codes for "Illegal" pressure switch combinations.

The TCM can calculate actual ratio by comparing Input Speed to Output Speed....But the monitor isn't constantly active. Used mostly for TCC Slippage calculations. At most this monitor would cause a Incorrect Ratio code for the way it's acting.

 

[WyrTwister]

Guessing the transmission will need to be pulled to diagnose / repair ?

Please refresh my memory . How many miles on the vehicle ?

 

[Imp4]

Originally Posted By: WyrTwister
Guessing the transmission will need to be pulled to diagnose / repair ?

Please refresh my memory . How many miles on the vehicle ?

Per OP's original post, it's an '06 HHR with 184k.
Most appropriate this here is to take your wallet and run in the opposite direction. (And that's coming from a guy driving an '01 Galant

).

 

[clinebarger]

Originally Posted By: WyrTwister
Guessing the transmission will need to be pulled to diagnose / repair ?

Please refresh my memory . How many miles on the vehicle ?



If the problem is in the Side Cover.....

The service manual will tell you to completely remove the transaxle that calls for around 8 hours, A good tech that's familiar with this unit/platform will remove the right Knuckle/Strut & axle, Support the engine/transaxle assembly.....Then lower the Subframe/engine/transaxle enough to remove the Side Cover. I can do it in around 3-5 hours depending on what I'm replacing.

 

[Gasbuggy]

Can you manually shift it while driving?