Cruise Control Will Not Engage
- Turn ignition off. Disconnect cruise control module connector. Turn ignition on. Connect a test light between cruise control module connector terminal "F" (Brown wire) and ground. See Fig 1
. If test light glows, go to next step. If test light does not gl ow, check for open or short to ground in Brown wire.
- Connect test light between cruise control module connector terminals "F" (Brown wire) and "E" (Black/White wire). If test light glows, go to next step. If test light does not glow, repair open in Black/White wire.
- Ensure ignition switch is still in RUN position. Set cruise control slider switch to ON position. Connect test light between ground and cruise control module connector terminals "B" (Dark Blue wire) and "C" (Dark Green wire). If test light does not glow at either terminal, go to next step. If test light glows at either terminal, check for a short to power in Dark Blue and Dark Green wires. If circuits are okay, replace cruise control switch.
- Connect test light between cruise control module connector terminal "A" (Gray wire) and ground. If test light glows, go to next step. If test light does not glow, backprobe between terminal "A" (Brown wire) of 4-pin connector at cruise control switch and ground. If test light does not glow, repair open or short to ground in Brown wire. If test light glows, check for open in Gray wire. If circuit is okay, replace cruise control switch.
- Connect test light between cruise control module connector terminal "D" (Brown wire) and ground. If test light glows, go to next step. If test light does not glow, backprobe between cruise control release switch terminal "B" (Brown/White wire) and ground. If test light does not light, repair open in Brown/White wire between switch and fuse block. If test light glows, check for open in Brown wire between switch and module.
- Connect test light between cruise control module connector terminal "G" (White wire) and ground. If test light does not glow, go to next step. If test light glows, disconnect brakelight switch. Connect test light between brakelight switch connector terminal "A" (Orange wire) and ground. If test light glows, repair short to power in White wire. If test light does not glow, check brakelight switch adjustment. If adjustment is okay, replace switch.
- Connect test light between cruise control module connector terminal "B" (Dark Blue wire) and ground. Press and hold SET switch. If test light glows, go to next step. If test light does not glow, backprobe between 4-pin cruise control switch terminal "D" (Dark Blue wire) and ground. Press and hold SET switch. If test light does not glow, replace cruise control switch. If test light glows, check for poor connection or open in Dark Blue wire.
- Turn ignition off. Reconnect cruise control module connector. Disconnect Powertrain Control Module (PCM) connector "B". Turn ignition on. Measure voltage between PCM connector "B", terminal No. 8 (Dark Green/White wire) and ground. If voltage is about 7 volts, go to next step. If voltage is not about 7 volts, check for poor connection, short to ground, or open in Dark Green/White wire. If circuit is okay, replace cruise control module.
- Turn ignition off. Reconnect PCM connector. Set parking brake. Start engine. Move cruise switch to OFF, then ON position. Wait at least 3 seconds, then go to next step.
- Push cruise switch in and hold. On Roadmaster, CRUISE indicator should light momentarily. On all models, hold cruise switch in R/A position. Fully depress and hold brake pedal. On Roadmaster, CRUISE indicator should light for 5 seconds. On all models, after 10 seconds, release brake pedal while holding R/A and SET switches. If engine RPM does not momentarily increase, replace cruise control module. If engine RPM does momentarily increase, check for poor connection at PCM connector "B", terminal No. 8 (Dark Green/White wire). If connection is okay, replace PCM.
Courtesy of GENERAL MOTORS CORP.