4L80 L/U problem [Archive] - Diesel Place : Chevrolet and GMC Diesel Truck Forums

: 4L80 L/U problem


lassefromdenmark
03-08-2006, 04:51 AM
Hi,

My ´92 Chevy with 6.2 L Diesel engine is equipped with a 4L80 transmission. The mileage is approx. 200,000. When the engine/trans. is warm (after 10-20 min. driving), it starts shifting from lock-up to 3rd, back and forth. Simultaniously the service engine soon light flashes.

I changed the fluid and filter, no succes. There was no burned smell from the old liquid and no metaldust/parts on the magnet. My mechanic read out the codes, and nothing there either. It shifts very smoothly all the way up to 4th (lock-up).

I suspect an electrical problem, but don't know where to look? Does anybody have a suggestion?

Rgds.

Lasse