Transmission shifts at inappropriate RPM
I have a 1991 2500 4x4 Chevy Suburban. Local mechanic came up with shift
solenoids bad per code reader. Took to Aamco and mechanic drove vehicle and
diagnosed a late and harsh 2-3 and 3-4 shifts.Transmission checked good, however
Aamco could not communicate with computer. Recommended to have electrical
test.Took to auto electrical specialist and both shift solenoids tested fine, computer
changed and problem still exists. Possibility of bad PROM, however PROM not
manufactured anymore. Local mechanic researched and found similar vehicle with
exact problem. Transmission wire harness was changed. Seemed to fix problem. Need
advice on possibly finding PROM or thoughts on wire harness.
Finally took to dealer and sure enough, wire harness was shorting out. Harness changed, runs great.
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