Blue93cube
Newbie
New to the forum but have been reading a ton. 1993 G30 van, ex air force, 6.2/4L80E. Problems started with dead TCU, limp mode, CEL, was run this way for a while (off road only maintenance support vehicle). Replaced TCU, swapped chips. Now have 1st, no CEL, but no upshift. Not in od, d, or trying manual 1-2. Replaced and reset tps (before TCU) which had big dead gaps, both speed sensors, and 1-2 solenoid. Fluid looked good, light deposits in bottom of pan, nothing to note in filter. Recently, occasionally, under light throttle at mid rpm’s, 15-30 mph, on the level, it will seem to upshift then within a second or two, drop back down again, however, there is no engine braking when it drops under those circumstances. If a scan tool is the next stop, wondering if someone in the Pittsburgh area has one, or if there is a shop that can be trusted with the obd1 (incl diesel) stuff.