LEMON Manuals: Even more car manuals for everyone
Home >> GMC >> 1997 >> C3500 HD 6.5 F, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System & Component Tests - 7.4L >> Miscellaneous Pcm/VCM Controls >> Transmission >> Shift Light (Manual Transmission)

Shift Light (Manual Transmission)

  1. These tests assume a shift light problem exists. Use this procedure only if the light will not illuminate, or illuminates all the time.
  2. Turn ignition on, with engine off. Note shift light. Shift light should not be on. If shift light is on, check for a short to ground between bulb and PCM/VCM or for bad PCM/VCM.
  3. Turn ignition on, with engine off, ground test terminal No. 2 (Purple wire) of Data Link Connector (DLC). Malfunction Indicator Light (MIL) should flash and shift light should come on. If MIL illuminates, go to next step. If MIL does not flash, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in the BASIC TESTING - 7.4L article.
  4. If shift light does not come on, ground Tan/Black light driver wire at PCM/VCM terminal using a jumper wire. For circuit identification, see SHIFT LIGHT CIRCUIT IDENTIFICATION table. See Fig 1 .
  5. If shift light still does not come on, check for blown GAGES fuse, blown bulb or open circuit between fuse and PCM/VCM. If shift light illuminates when grounding PCM/VCM terminal with a jumper wire, problem is a bad PCM/VCM connection or bad PCM/VCM.
SHIFT LIGHT CIRCUIT IDENTIFICATION

Application VCM Connector (Terminal No.)
"C" & "K" Series C4 (15)
Fig 1: Typical Shift Light Circuit
G95C35545Courtesy of GENERAL MOTORS CORP.