LeafDriver
New member
- 1
- 0
- 1
- Location
- Canada
Hi, first time poster long time lurker.
I've been sifting through many threads and the Gear-report 4l80e troubleshooting guide on this particular problem but I've not found a solution yet so I'm posting this SOS before I resort to pulling the entire transmission out.
My Hmmwv is a 2003 M1123 (converted to fastback) 6.5 N/A 4L80e
Problem: DTC 86 (limp mode), occasionally stalls at stop when in drive/reverse. Engine running well, still drive-able at low speeds.
Here's the order of events:
On the way back from a long trip I suddenly noticed the transmission would not lock the TC into overdrive, checking the fluid I didn't notice anything unusual and stopping/starting again after 30 minutes the problem seemed to resolve itself, tried pulling codes, got only 12 on repeat. Went for a test drive the following morning I found the truck seemed to be stuck in Limp mode, 2-3 no TC lock no 1st gear, stopped there found the fluid had turned dark red and had a different odor, DTC 86 first appeared here. Checking the Transmission harness pass-through connector I found fluid inside the plug, so I thought this was the cause.
Dropped the pan, fluid was dark red, a light smell of burnt rubber, some dark sludge, no metal chunks in pan or on magnet.
After some fix hunting and wrenching I decided to replace the internal harness as well as all the solenoids, the TISS/TOSS and also the TPS.
I got DTC 22 while I was adjusting the TPS but cleared it once I got the correct adjustment.
Put it all back together, added new fluid and cleared codes again.
Drove it the same night and everything worked beautifully, it seemed to be fixed. Observed a smooth 1-2-3-4 shift/TC lockup at highway speed no problem. That seemed to be it yay.
Unfortunately, the day after I went for another test run and it was DTC 86 all over again. No up/down shift, TC dragging in drive/reverse occasionally.
Back to square 1. Nuts
Just about at my wit's end on this, anyone have any ideas?
Here's a nice picture for interest.
I've been sifting through many threads and the Gear-report 4l80e troubleshooting guide on this particular problem but I've not found a solution yet so I'm posting this SOS before I resort to pulling the entire transmission out.
My Hmmwv is a 2003 M1123 (converted to fastback) 6.5 N/A 4L80e
Problem: DTC 86 (limp mode), occasionally stalls at stop when in drive/reverse. Engine running well, still drive-able at low speeds.
Here's the order of events:
On the way back from a long trip I suddenly noticed the transmission would not lock the TC into overdrive, checking the fluid I didn't notice anything unusual and stopping/starting again after 30 minutes the problem seemed to resolve itself, tried pulling codes, got only 12 on repeat. Went for a test drive the following morning I found the truck seemed to be stuck in Limp mode, 2-3 no TC lock no 1st gear, stopped there found the fluid had turned dark red and had a different odor, DTC 86 first appeared here. Checking the Transmission harness pass-through connector I found fluid inside the plug, so I thought this was the cause.
Dropped the pan, fluid was dark red, a light smell of burnt rubber, some dark sludge, no metal chunks in pan or on magnet.
After some fix hunting and wrenching I decided to replace the internal harness as well as all the solenoids, the TISS/TOSS and also the TPS.
I got DTC 22 while I was adjusting the TPS but cleared it once I got the correct adjustment.
Put it all back together, added new fluid and cleared codes again.
Drove it the same night and everything worked beautifully, it seemed to be fixed. Observed a smooth 1-2-3-4 shift/TC lockup at highway speed no problem. That seemed to be it yay.
Unfortunately, the day after I went for another test run and it was DTC 86 all over again. No up/down shift, TC dragging in drive/reverse occasionally.
Back to square 1. Nuts
Just about at my wit's end on this, anyone have any ideas?
Here's a nice picture for interest.
