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Stuck In 2nd

MrGoodWreck

By MrGoodWreck
in Ask A GM Technician

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MrGoodWreck Enthusiast

MrGoodWreck

Posted
Posted

2005 Silverado SS - Engages hard into gear (both forward and reverse). Starts in third unless you pull it into low (1). When pulled into "1" it starts in 2nd and will shift to third when put in 3 or Drive. If left in 3 it will accelerate and decelerate with the engine. In Drive it will free wheel when off the gas.

 

It's been intermittant and now is a hard fault. Codes are P0 740, 753, 758, 761, 785 and P2761. It seemed to have the problem if the first thing I did was back up after starting.

 

It has power on pin E at the trans (pink wire). I dropped the pan and there is power to each solenoid. How do I troubleshoot the ground paths back through the PCM ? Any help out there ?

 

:cool:

cammiller Enthusiast

cammiller

Posted
Posted

The odds of all those codes being set are slim unless the the plug is off the side of the transmission. What did you use to test the power at the solenoids? If it was mine I would put a switch in it. They are very cheap- retail GM is $40 or so.

MrGoodWreck Enthusiast

MrGoodWreck

Posted
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Posted

Thanks - I inspected and cleaned both the trans connector and PCM connector. I measured voltage at the solenoid pins inside the trans so I conclude that the connector is not the problem - at least on the power side of the circuit. When this was first happening intermittantly, I replaced the switch module on the left side of the trans. but no change.

 

I think it must be on the ground side of the control circuit. They are all grounded through the PCM as far as I can tell. I also cleaned all the wire harness ground points on the chassis.

 

Any other thoughts ?

  • 1 month later...
gmtech04212007 New Member

gmtech04212007

Posted
Posted

Replace the ignition switch

It is problem that has to be explaind to understand

First of all the IGN 0 fuse in the fuse block inside the vehicle powers the 1 pink wire to the transmission connector. There must be battery voltage at that wire... 12 volts ... no less

now that 1 wire splits up into 5 wires to power all the solenoids in the transmission.

Each of the solenoids have their own ground through the pcm

When all these codes set it is hard to believe the pcm is the issue due to 5 seperate ground wires (possible but unlikely) What ususlly happens is an interminent short in the ignition switch the powers the ING 0 fuse

this short or open only has to last for 3 seconds and the code pops

during this time the power can go back to normal (switch powers the correct voltage) but tranny goes into limp mode untill codes cleared

 

so my advice put in a 50 dollar ignition switch

 

and let me know how it works out

minibike132 Senior Enthusiast

minibike132

Posted
Posted

+1 on the switch, if it is a hard fault now you can check that circuit. If it was intermittant I would throw one at it based on about 100:1 odds. If it's happening now check out the circuit just to be sure.

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