Hi, new to this forum and hoping someone can give me some pointers for troubleshooting the Allison transmission output speed sensor and circuitry to the transmission controller. It's a 2002 Silverado 3500, 4WD, with the big 8.1 engine and Allison automatic transmission. Should also mention that this is a baby dump truck. Transmission one day would not shift out of 1st gear and speedometer does not work. Fault codes are P0700 & P0722. Output speed sensor was replaced with no change. No dirt build up on the old one and connection looked good. The speed sensor is a simple 2-pin so probably a frequency output. Thought about putting it on jack stands and running it with the wheels off the ground to look at the sensor output but figure that is not the most likely cause and not that crazy about doing it without getting access to a secure lift and need sensor details to know what I am looking for. Did repair a damaged wire underneath (soldered and heat shrink) but not connected to the failed speed sensor circuit. Is there anything else connected to the speed sensor circuit or is it just a straight input to the controller? Could someone point me to a wiring schematic or provide pin-outs for the controller? Figured better to start by checking wiring continuity. Any other suggestions will be appreciated.
Thanks,
AL
Thanks,
AL
