gotaconvoy
Member
- 42
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- Location
- FL
Howdy. I just finished a 2 year rebuild and took the Humvee for a test drive after getting it registered. One aspect of the rebuild was having the transmission rebuilt at a reputable transmission shop (bench rebuild with no test drive at time of rebuild). During my recent test drives, the trans shifted from 1st to 2nd, then stayed in second the remainder of the drive.
Truck:
1996 M1097A2
6.5 non-turbo
4l80e
Codes:
Trans light comes on with key on / not running, and goes off once the truck is running. Using a jumper at the test port I get codes 73 (PCS Circuit) & 87 (High Ratio Error).
Diagnostic steps taken so far:
Using wiring schematics from the 4l80E manual (https://gear-report.com/wp-content/...ment_7_4L80E-Transmission_Troubleshooting.pdf), I verified all the appropriate voltages and grounds were present at the TCM, trans relay and breaker.
Followed the DVOM diagnostics steps for code 73 as outlined on page 101 of the TM. Basically confirming continuity in the two wires between the TCM and trans plug, then confirming PCS resistance (4.3 ohms). Everything had continuity and ohms were within specs but the flowchart stops there.
I do not have a tech2 scanner, or any other equivalent to interrogate the TCM in order to follow the diagnostic steps for code 87.
Points to note:
After purchase (govplanet), I think this was a parts truck in a depot somewhere that slowly got cannibalized and when it was time to sell they threw whatever parts they had lying around back into it. I'm pretty sure the trans I bought it with may have come from another truck due to it being halfway installed with missing hardware and very much inoperable.
Additionally, the TCM part number in the truck is TCM-2100AA, which all the research indicates is for a turbo engine, and mine is naturally aspirated.
Next steps:
Here's where one of you lovely folks hopefully comes in because I don't know where to go next. I was about to buy some tech2 clone, an old obd1 port, and try and talk with the TCM but I figured I'd ask around first before going crazy. Any ideas?
Truck:
1996 M1097A2
6.5 non-turbo
4l80e
Codes:
Trans light comes on with key on / not running, and goes off once the truck is running. Using a jumper at the test port I get codes 73 (PCS Circuit) & 87 (High Ratio Error).
Diagnostic steps taken so far:
Using wiring schematics from the 4l80E manual (https://gear-report.com/wp-content/...ment_7_4L80E-Transmission_Troubleshooting.pdf), I verified all the appropriate voltages and grounds were present at the TCM, trans relay and breaker.
Followed the DVOM diagnostics steps for code 73 as outlined on page 101 of the TM. Basically confirming continuity in the two wires between the TCM and trans plug, then confirming PCS resistance (4.3 ohms). Everything had continuity and ohms were within specs but the flowchart stops there.
I do not have a tech2 scanner, or any other equivalent to interrogate the TCM in order to follow the diagnostic steps for code 87.
Points to note:
After purchase (govplanet), I think this was a parts truck in a depot somewhere that slowly got cannibalized and when it was time to sell they threw whatever parts they had lying around back into it. I'm pretty sure the trans I bought it with may have come from another truck due to it being halfway installed with missing hardware and very much inoperable.
Additionally, the TCM part number in the truck is TCM-2100AA, which all the research indicates is for a turbo engine, and mine is naturally aspirated.
Next steps:
Here's where one of you lovely folks hopefully comes in because I don't know where to go next. I was about to buy some tech2 clone, an old obd1 port, and try and talk with the TCM but I figured I'd ask around first before going crazy. Any ideas?
