Transmission problem
1999 GMC Jimmy 6 cyl Four Wheel Drive Automatic

i have recently rewired a 99 gmc jimmy at the power dist. block and at the pcm. I used the mitchall manner diagrams. i have cheked all the wires three times and i'm still having problems with the torqueconverter locking up as soon as it shifts out of 1st gear going into 2nd. the speed sensor calls for 5volts and i am only getting 0.64volts. i have replaced the pcm and still have the same problem.i have scanned it for troble codes but come up with nothing. the "check engine" light gos off like it is supossed to. the engine runs fine.where does this problem sound like it may start

Hi:

It sounds like the speed sensor is bad, or you have a broken wire. Did you replace the speed sensor?

Joe

Hi Joe
This is the guy with the 99 gmc jimmy again. I have put my scan tool (Actron Elite Auto Scanner CP9185) it seems to communicate with all systems and it tells me no faults detected. I have also checked the speed with the scanner and it matches the speedometer with scan tool in drive mode. I got 4.0-5.0 volts at the VSS I would think that the VSS checks out to be ok. The wiring harness has been taking out of the jimmy and checked with a continuity by digtial meter and couldn;t find any broken or crossed wires. every thing in the jimmy works, except for this shifting problem. Any ideas about pusle width module but it seems like a DTC code would make the light come on. Im out of ideas. PLEASE HELP.

Hi:

I reviewed your original question and it indicates that you're only getting 0.64 volts and should be getting 5 volts. Is that in or out? Is there any way you find a different one just to try? Not being there with you is making this even harder, but I truly question if that is what is causing your problem. Regardless, I don't want you to spend the money and it not fix the problem.

Let me know what you think and get back to me. While you think of that, I will contact some of the other moderators and get their opinion. WE WILL FIGURE THIS OUT!

Joe

Which sensor exactly is only getting .64 volts?
Are you positive which ever sensor it is, is located at the correct pin at the PCM? If the wire checks out ok, that is the first thing that comes to mind....especially if the PCM has been changed

Disconnect the TCC solenoid and see what happens-also test the brake switch and the TPS sensor

the Transmission Control Solenoid has alot to do with Torque Converter lock up can you test this and let us know what you get from test

Hi Joe
Here I am back with the same 99 Gmc Jimmy with the same shifting problem. I have sent the Jimmy to Amco transimissons & he put it on his trans scanner on it and he told me that mechanically the tranny was ok. I have checked the vss, iss and the oss and all three sensors will give me ac signal back to the pcm. with the rear tires off the ground in drive running about 15 mph i have checked for 5 volts at the vss and also the pcm plug and all i have is .64 volts so i jumped 5 volts from the reference wire off of the mass air flow sensor to the vss and still same problem i have been told by one person that it calls for 5 volts and another person said it called for 12 volts. What voltage does the vss call for and is there any reason for the pcm to only give me .64 volts on the vss signal wire. The tps seems to be operating smoothly on the scanner i also put a new brake switch on and still no difference. All circuts to each of these sensors have convity back to the pcm. I am ready to shoot this jimmy and get it over with. Do you have any more ideas if you do please help iam running out of ideas on this truck