01 Jimmy Trans Lag
Question:
Change the fluid and filter, a new trans makes lots of dirt, break in shavings and clutch dust. For maximum trans life, add a drain plug and go to synthetic fluid. Conventional fluid breaks down forming varnish on clutch plates. Synthetic fluid " laughs off" heat, keeps parts clean. One last point, check all electrical and vacuum fittings, a leaky line, or a loose electrical connection can start problems that vastly shorten trans life. The secret to long transmission life is full line pressure = tight clutch engagement.
Response:
Try Sonnax.com, there is a modification kit for these troublesome valve body problems that most good trans shops should be aware of.
> Hello, > I have noticed my 2001 Jimmy has progressively adopted a transmission lag > between up-shifting gears. It used to do it about a month ago on steep > hills and now even on low grade it will "hesitate in neutral" before > engaging the next gear. > I originally thought it may need a trans fluid flush, but with only 20,000Km > on an automatic transmission I think its a little early for that. > Any suggestions before the dealer takes a look? > Thanks > 2001 GMC Jimmy SLT 4WD
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Response:
Wasn’t a TSB put out by GM calling for replacement, not rebuilding, of the valve body? Possibly the case for later models… – Hide quoted text — Show quoted text – > If your transmission also ‘bumps’ or ‘jolts’ when shifting up to the next > higher gear, you may have a similar or identical problem to what we have > been experiencing with my wife’s ‘95 Blazer with the 4L60E tranny. For > whatever reason, a problem with the valve body has the tranny is sensing a > load and commanding max line pressure to make the upshifts, causing the > hesitation between gears (most noticable between first and second at very > slow speeds) and the bump when upshifting (also most noticable between first > and second in most any speed, especially when cold). Two valve body > rebuilds later, however, and the problem persists. A bottle of Greased > Lightning transmission additive has reduced the symptoms somewhat but not > eliminated the problems entirely. > Good luck – Jonathan > — > Acta Non Verba – Deeds Not Words > Lieutenant Jonathan Race, EMS Supervisor > Orange County (FL) Fire-Rescue Department >Hello, >I have noticed my 2001 Jimmy has progressively adopted a transmission lag >between up-shifting gears. It used to do it about a month ago on steep >hills and now even on low grade it will "hesitate in neutral" before >engaging the next gear. >I originally thought it may need a trans fluid flush, but with only > 20,000Km >on an automatic transmission I think its a little early for that. >Any suggestions before the dealer takes a look? >Thanks >2001 GMC Jimmy SLT 4WD
Response:
If your transmission also ‘bumps’ or ‘jolts’ when shifting up to the next higher gear, you may have a similar or identical problem to what we have been experiencing with my wife’s ‘95 Blazer with the 4L60E tranny. For whatever reason, a problem with the valve body has the tranny is sensing a load and commanding max line pressure to make the upshifts, causing the hesitation between gears (most noticable between first and second at very slow speeds) and the bump when upshifting (also most noticable between first and second in most any speed, especially when cold). Two valve body rebuilds later, however, and the problem persists. A bottle of Greased Lightning transmission additive has reduced the symptoms somewhat but not eliminated the problems entirely. Good luck – Jonathan — Acta Non Verba – Deeds Not Words Lieutenant Jonathan Race, EMS Supervisor Orange County (FL) Fire-Rescue Department
– Hide quoted text — Show quoted text -> Hello, > I have noticed my 2001 Jimmy has progressively adopted a transmission lag > between up-shifting gears. It used to do it about a month ago on steep > hills and now even on low grade it will "hesitate in neutral" before > engaging the next gear. > I originally thought it may need a trans fluid flush, but with only 20,000Km > on an automatic transmission I think its a little early for that. > Any suggestions before the dealer takes a look? > Thanks > 2001 GMC Jimmy SLT 4WD
