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Discussion Starter · #1 · (Edited)
Hey everyone....2009 Base going into limp mode. Did a maint kit on the transmission. No help. Replaced the 3 sensors in the transmission. No help. Replaced and re-programmed a used TCM. No help. The only thing left is the internal wiring harness but we cant find one. Any ideas?
 

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There are transmission issues that arise on automatic cars when the engine's variable valve timing solenoids are defective or clogged. Though I'm not sure what codes it usually throws and whether the transmission goes to limp mode. Someone more experienced may chime in. Did you have any hard or clunky/choppy downshifts? Cos these are VVT solenoid symptoms.
 

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Discussion Starter · #6 ·
There are transmission issues that arise on automatic cars when the engine's variable valve timing solenoids are defective or clogged. Though I'm not sure what codes it usually throws and whether the transmission goes to limp mode. Someone more experienced may chime in. Did you have any hard or clunky/choppy downshifts? Cos these are VVT solenoid symptoms.
No...It just went into limp mode a few times. I took it to AAMCO instead of my mechanic. Not pleased.
 

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2008 Pontiac Solstice GXP - Mysterious (with unkown origin blue sparkle in rear bumper cover paint)
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Does the solstice auto have a “manual” mode (sorry I have a stick so not sure)
If it does have the manual mode, can you drive relatively normally by selecting gears on your own?
Most of what people can offer to help is going to be guessing unless you can provide A list of active and pending codes.
A deeper description of the symptoms would be helpful as well…
 

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Discussion Starter · #10 ·
Does the solstice auto have a “manual” mode (sorry I have a stick so not sure)
If it does have the manual mode, can you drive relatively normally by selecting gears on your own?
Most of what people can offer to help is going to be guessing unless you can provide A list of active and pending codes.
A deeper description of the symptoms would be helpful as well…
Normally yes its a typical auto trans but once it goes into limp mode it wont shift to a different forward gear. It stays in low gear. It was running fine and then randomly went into limp mode. You can move the stick shift but the forward gear wouldn't change. It would go backwards normally though.
 

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when the cam position servos go bad, the transmission goes into protection mode., It exhibits very abrupt and hard downshift from 3rd to 2nd or 2nd to 1st
 

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Discussion Starter · #12 · (Edited)
when the cam position servos go bad, the transmission goes into protection mode., It exhibits very abrupt and hard downshift from 3rd to 2nd or 2nd to 1st
Not getting any hard shifting or abrupt behavior. Just goes into limp mode. it's done it going 70 on the highway. Nothing weird, it would just wouldn't down shift when you tried to pass. Or went into limp mode after sitting at a light. Would gradually pick up speed but stayed in a low gear.
 

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2008 Pontiac Solstice GXP - Mysterious (with unkown origin blue sparkle in rear bumper cover paint)
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Though it is likely not relevant pulling the VVT solenoids and checking (if you haven’t already) is a really simple step to take, if nothing more than to cross it off your list…
 

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p0979: 4-5 shift solenoid control circuit low voltage

conditions for setting the DTC:
The TCM detects an open in the 4-5 shift solenoid valve circuit when HSD2 is commanded ON
The TCM detects a short to ground in the 4-5 shift solenoid valve circuit when HSD2 is commanded OFF

Description of Circuit:
The 4-5 shift solenoid valve is located in the control valve body of the transmission. The TCM selects the required gear by turning the appropriate valve ON or OFF which enables the transmission to shift. The TCM provides voltage through high side driver 2 (HSD2). The TCM uses a second driver to control the solenoid ground circuit. The controlled ground driver reports feedback voltage to the TCM. When the TCM commands the 4-5 shift solenoid valve ON, the voltage of the control circuit should be approximately 0 volts. When the TCM commands the 4-5 shift solenoid valve OFF, the voltage of the control circuit should be approximately system voltage.

the "driver" term used above is the power supply used to control the circuit. There are 2 drivers (power supplies) involved. One that handles putting out a positive voltage and the second one puts out a ground. The one that puts out the positive voltage is an "always ON" and the ground state being turned on and off is what turns the valve ON and OFF. The ground circuit is also used to test if the solenoid is good or bad. When the ground driver is not outputting a ground signal the side of the solenoid it is connected to should read close to the same voltage as what is being put into it from the positive driver. If it is not that means there is an open or a broken connection.

This is what I believe you have going on. Your 4-5 shift solenoid is no good. It appears to be random or intermittent but more then likely it is not. There is a bad connection in the solenoid that when cold it works fine and once the transmission heats up expansion occurs the connection opens up and the DTC gets set. You can test this theory by getting the car into 5th gear while it is cold and monitoring the engine temperature and when it does it record what the engine temp is. Do this several times and see if there is any consistency to the temperature readings. The temperature of the transmission is going to lag behind what the engine temperature is and it may only occur once the engine has been up to temperature (195 to 205) for a little bit before it occurs. The fact that it only occurs once the vehicle is up to temperature is the symptom and it points to a bad control valve in the transmission.
 
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you would think they should know how to diagnose a bad shift solenoid.
 
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I would have to look up how difficult it is to access the valve body. On some transmissions it is a matter of pulling the filter pan and others you have to pull the entire transmission out of the car and take the thing apart to get to it.

If the transmission has to be pulled in order to access it you might consider at that point just having them do a complete rebuild of the thing. Most of the money is going to be in the removal and installation of the transmission so it almost makes sense to have the thing gone through and have all of the shift solenoids replaced and the clutch packs replaced. I would also have them inspect for parts that are showing any wear and replace those as well.

It's gonna get expensive if they have to pull that transmission out.
 
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