SOURCE: 4l60e 2000 gmc tRANSMISSION PROBLEM
Replace the solenoid pack, or the wiring to the trans has problems. Usaully the solenoid pack in our Chrysler trans, but every once in a while, it is bad wiring.
SOURCE: 95 GMC Truck Transmission, 5.7 Motor
It sounds like the engine and transmission needs to be recalibrate to one another. I good transmission shop with a tech 2 scanner can fix this if it's not a mechanical problem. Here is 101 transmission in a few words that i hope can help you. The Throttle position sensor (TPS) sends signals to the ECM and calculate with the transmission turbine sensor (VTS)the amount of transmission line pressure which is controlled by the transmission line pressure servo. The pressure line servo controls the firmness of the shift and the TPS with the VTS controls the shift points. If the ECM is not calibrated or a senor is reading bad your going to have problems with the transmission like you have and will have a major failure within 6 month due to burnt clutch packs, so check your transmission fluid for leave and condition. It should be bright red and not dark like burgundy which would indicate burnt clutch packs. If there is a good transmission shop or you have warranty on your transmission, have them do a transmission line pressure and scan the ECM for any DTC codes. IF your out of warranty, find a good speed shop who can read and reprogram your ECM so you can have your engine and transmission running 100% Good luck and hope this helps.
SOURCE: i have a 97 gmc jimmy 4x4. the transmission goes
I need the CODES this year has valve body problems for tcc slipping on these & shift timing need more information
SOURCE: I have a 1992 gmc
CODE 42
Trouble Code 42 indicates that there may be a malfunction in the Electronic Spark Timing (EST) system.
During cranking, the timing is controlled by the ignition module
while the ECM monitors the engine speed. When the engine speed exceeds
400 RPM, the ECM sends a BYPASS signal to the ignition module which
switches the timing to ECM control. The ECM calculates what the timing
should be then "tells" the ignition module via the EST circuit.
An open or ground in the EST circuit will stall the engine and set a
Code 42. The engine can be re-started but it will run on ignition
module timing.
The conditions for setting this code are:
- or -
Typical causes for this code include:
1) BYPASS line is open or grounded
2) EST line is open or grounded
3) PROM or CALPACK not seated properly in the ECM
4) Poor connections between ignition module and ECM
5) Poor routing of EST harness and/or poor quality ignition wires (EMI induced electrical noise)
6) Faulty or incorrect ignition module
7) Faulty ECM
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Inspect the transmission fluid for debris.
DTC P0742 Torque Converter Clutch System Stuck ON Step
Action
Value(s)
Yes
No
1
Was the Powertrain On-Board Diagnostic (OBD) System Check performed?
--
Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check
2
Install the Scan Tool .
With the engine OFF, turn the ignition switch to the RUN position.
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records for reference. The Clear Info function will erase the data. Record the DTC Freeze Frame and Failure Records, then clear the DTC.
Start and run the vehicle.
Select TCC Slip Speed on the scan tool.
With the transmission in D4, drive the vehicle through the 1-2 upshift.
In second gear is the TCC Slip Speed within the range specified?
-20 to +50 RPM
Go to Step 3
Go to Diagnostic Aids
3
Inspect for the following conditions:
The TCC apply valve stuck ON because of sediment or damage.
The TCC Sol. Valve Assy. stuck ON because of sediment or damage. Refer to Control Valve Body Assembly Inspection, in Unit Repair.
Was a condition found and corrected?
--
Go to Step 4
--
4
In order to verify your repair, perform the following procedure:
Using the scan tool, clear DTCs.
Operate the vehicle under the following conditions:
• The gear range is D2, D3 or D4.
• The commanded gear is not 1st.
• The engine speed is greater than 500 RPM for 5 seconds.
• Not in fuel shut off.
• The engine torque is 95-270 N·m (70-200 lb ft).
• The throttle position is 14-50%.
• The PCM commands the TCC OFF.
• The TCC slip speed is 150-2000 RPM for 5 seconds.
• The engine speed is 800-4000 RPM.
• The vehicle speed is 32-112 km/h (20-70 mph).
• The speed ratio is 0.65-1.18.
• The last gear change occurred more than 3 seconds ago.
Select Specific DTC. Enter DTC P0742.
Has the test run and passed?
--
System OK
Begin the diagnosis again. Go to Step 1
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