2000 Chevy Silverado trans won't shift when hot

NOEL BEGLEY

MEMBER
2000 CHEVROLET SILVERADO

Transmission problem
2000 Chevy Silverado V8 Four Wheel Drive Automatic

I have a silverado 6 litre Diesel that had an alison Auto gear box.
Had a second hand motor fitted and since then the gear box when cold changes and kicks down. But when it heats up it stays in top gear untill I stop and change the gear shift to park or reverse and then it just stays in 1st gear. When it is cold again it is O.K. When it is staying in top gear I can stop and it will take off in top gear unless I move the gear shift. There is a gear tempature gague on the dash for the gear box and it seems to be working as when cold it reads cold and after driving for 15 minutes or so it comes to about half way. The only oter thing I have noticed is the oil pressure gague for the motor reads past full at all times when the motor is running.
Your sugestions would be appreciated. NOEL.

5 Replies

DENNYP

MECHANIC
1,823 POSTS

I was reviewing your question and am unable to find that engine/transmission combination for that model year silverado. Can you verify the information for us or provide the full VIN. Thanks, DennyP

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Friday, October 8th, 2010 AT 4:51 PM

NOEL BEGLEY

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Hi Denny it is a 2001 6.6 litre diesel turbo and has just had a 2005 motor fitted. The vin number is 1GCHK231X1F120058. The gears were all O.K. Before the motor was swapped. It has an Allison gear box. The mechanic shop that fitted the motor were not interested in the complaint about this and have been paid for the fitting of the motor. I have since found a lot of pipes loose and even the pipe from the turbo to the intercooler was off. Is there a fault diagnostic for the gear box as I have a scann tool? Thanks: NOEL.

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Wednesday, October 13th, 2010 AT 2:08 PM

DENNYP

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This is going to be a tough one. You are going to need to scan the transmission for trouble codes with a Tech 2 scanner. (This is the only one I can guarantee to read allison trouble codes in a GM product)
Make sure all of the charged air cooler tubes are sealed and tight. They can't have even the slightest leak.
Let me know what codes you have. I am expecting to see a code for a shift solenoid or the gear range selector.

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Thursday, October 14th, 2010 AT 7:17 PM

NOEL BEGLEY

MEMBER
21 POSTS

PUT ALL THE PIPES FOR THE TURBO BACK ON AND IN THE CORRECT PLACES AND NOW THE GEARBOX IS GOING PERFECTLY. MUST HAVE PICKED UP AN AIR FLOW FAULT AND THEN PUT THE GEARBOX AND MOTOR CONTROL INTO A LIMP MODE.
THANKS FOR YOUR HELP.
I HAVE ANOTHER SILVERADO THAT IS PETROL AND RUNS ROUGH AND STOPS WHEN HOT. IT IS A V8 SPI AND SHOWS FAULT AIR FLOW AND CAM SENSOR. CLEARED CODES AND RAN MOTOR. NOW THERE IS ONLY CAM SENSOR FAULT. WHEN COLD RUNS O.K. WHEN HOT MISSES AND THEN MOTOR STOPS AND WON, T START UNTIL COLD. HAS HAD PLUGS LEADS COIL AND THE SINGLE POINT INJECTORS REPLACED. WHERE IS THE CAM SENSOR LOCATED OR IS IT A CRANK SENSOR WE ARE LOOKING FOR?Thanks: NOEL

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Sunday, January 9th, 2011 AT 2:08 AM

DENNYP

MECHANIC
1,823 POSTS

If it is an engine with a distributor, the cam sensor is the pickup coil in the distributor. You might also want to remove the distributor to inspect the drive gear for wear.