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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1327 (Automatic Transmission - Mu4 (Introduction, Service & Replacement)) >> Diagnostic Information and Procedures >> Overdrive Off Indicator Inoperative >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

  1. 1:  The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
  2. 2:  This step checks the O/D OFF indicator light by jumping the switch to ground.
  3. 3:  This step checks the ground circuit and the Overdrive switch.
  4. 4:  This step checks for an open LT GRN wire or an open indicator bulb.
Overdrive Off Indicator Inoperative

Step Action Yes No
Schematic Reference: Automatic Transmission Controls Schematics 
1  Was the Powertrain On-Board Diagnostic (OBD) System Check performed? Go to Step 2  Go to Diagnostic System Check - Engine Controls in Engine Controls
2  Backprobe the Overdrive switch connector with a fused jumper wire from cavity 2 to ground.
Turn the ignition switch ON.
Does the O/D OFF indicator light?		 Go to Step 3  Go to Step 6 
3  Backprobe the Overdrive switch connector with a test lamp from cavity 4 to B+.
Does the test lamp light?		 Go to Step 5  Go to Step 4 
4  Backprobe the Instrument Cluster connector cavity 13 with a fused jumper to cavity 4 on the switch.
Does the O/D OFF indicator light?		 Go to Step 7  Go to Step 8 
5 Replace the Overdrive switch.
Is the action complete?		 Go to Step 9  -
6 Inspect for an open in GRN/BLK wire between the Overdrive switch harness connector and the PCM.
Is the action complete?		 Go to Step 9  -
7 Inspect for an open in LT GRN wire between the Instrument Cluster and the PCM or in GRN/BLK wire between the PCM and the Overdrive switch.
Is the action complete?		 Go to Step 9  -
8
  1. Inspect the Instrument Cluster printed circuit for cracks or poor connections.
  2. If OK, replace O/D OFF indicator bulb.
Is the action complete?		 Go to Step 9  -
9
  1. Turn the ignition switch to LOCK.
  2. Reconnect all disconnected connectors.
  3. Turn the ignition switch to the ON position.
  4. Press and release the Overdrive switch while observing the O/D OFF indicator.
Does the O/D OFF indicator light toggle from on to off?		 System OK Go to Step 1 
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