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Home >> GMC >> 1997 >> Forward Control 7.4 J >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 10 (Cruise Control System - Diesel (P Series)) >> Testing >> Cruise Control Is Inoperative
July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

Cruise Control Is Inoperative

WARNING: This page is about a different variant/trim than selected.
  1. Ensure I-3 (15-amp) and STOP/HAZ (15-amp) fuses are okay. Disconnect PCM. Connect test light between PCM connector C2, terminal B9 (Purple wire) and ground. Turn ignition on. If test light glows, go to next step. If test light does not glow, check TCC/brakelight switch adjustment. If adjustment is okay, check for open in Purple wire. If circuit is okay, replace TCC/brakelight switch.
  2. Connect test light between PCM connector C2, terminal B10 (Light Blue wire) and ground. If test light does not glow, go to next step. If test light glows, check TCC/brakelight switch adjustment. If adjustment is okay, repair short to power in Light Blue wire.
  3. Turn cruise control on. Connect test light between PCM connector C2, terminal A11 (Gray wire) and ground. If test light does not glow, go to next step. If test light glows, go to step 5).
  4. Using test light, backprobe between cruise control switch terminal "B" (Gray wire) and ground. If test light does not glow, go to next step. If test light glows, repair open in Gray wire.
  5. Using test light, backprobe between cruise control switch terminal "A" (Brown wire) and ground. If test light glows, replace cruise control switch. If test light does not glow, repair open in Brown wire.
  6. Connect test light between PCM connector C2, terminal B11 (Dark Blue wire) and ground. Press and hold SET/COAST button. If test light does not glow, go to next step. If test light glows, check vehicle speed sensor. If speed sensor is malfunctioning, a trouble code should be set. See TESTS W/CODES - 6.5L article in ENGINE PERFORMANCE section.
  7. Using test light, backprobe between cruise control switch terminal "D" (Dark Blue wire) and ground. Press and hold SET/COAST button. If test light does not glow, replace cruise control switch. If test light glows, repair open in Dark Blue wire.
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