01-30-2017, 09:49 AM
Good day....first off I know this is a Suzuki repair website n in my many years of experience I've never encountered a problem like this n worse no one with a real answer so please be courteous thanks. I have a 91 suburban 7.4L 4L80E a/t 2wd. Since day one of me taking possession of this vehicle ive had these 2 codes that refuse to go away.....DTCs 58 & 59-low & high voltage trans temp signal. DTCs 81 & 82 are intermittent. I rebuilt the trans found burnt friction clutches installed transgo hd-1 reprogramming kit replaced torque converter n all electrical sensors internal and external trans related wiring harnesses. Tested all new sensors. New TPS n properly adjusted, CTS, MAP O2 sensors EGR valve distributor plugs n plug wires insulated n new rewrapped engine wiring harnesses under hood reman cardone ECM (changed 3x now)first 2 ECM replacements showed 2v. Replaced wires from D2 ground pin and D15 trans temp 5v ref. Pin to trans harness connector. Voltage check indicates 7.3v at pin D15 5v ref. N at trans connector. All grounds on vehicle clean tight n checked. Trans works fine for awhile then intermittent 4th gear n lockup operation n hard n early shifts. Pressure gauge shows trans pressures within specs. I have no doubt this is a signal problem n the only component left that hasn't been replaced is the ECM prom which I would change if it was available. Any input would be appreciated n Im in so. Calif. N I don't know n cannot locate a company local that can make or reprogram my prom n ECM so that it works properly. If u know of a company that works n does these things on a obd1 ECM please share the info with me. No cel ever came on but blinks DTCs properly including 12s. Called cardone tech support n no help no suggestions but offered to replace ecms at no charge. Thanks