Today's electronically controlled automatic transmissions depend on good grounds for proper operation of the various solenoids and switches. Additionally, if there is a grounding problem sometimes the ground path will become the transmission detent, throttle valve or transhift cable. The current flow will burn the cable and cause it to fail.

Other times, the driveshaft or torque converter will become the ground path causing the bushings to fail. If you are replacing a transmission cable, check the grounds.

If your customer complains that the transmission seems to be shifting slowly, check the grounds. Battery, engine to firewall or frame and accessory grounds should all be inspected. If a ground carries voltage, there is excessive resistance somewhere in the ground circuit.

Inspect ground connections and clean as necessary. Many times an engine to firewall ground strap is disconnected or left off after an engine or transmission overhaul.

ATP No. Y-300, ground strap, can be used to replace missing or broken ground straps.