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Home >> GMC >> 1998 >> Yukon RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 70 (Automatic Transmission Diagnosis - 4L80-E (Gasoline)) >> Diagnostic Tests >> DTC P1860: TCC Pulse Width Modulated (PWM) Solenoid Electrical Malfunction >> Diagnostic Procedures

Diagnostic Procedures

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  1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
  2. If DTCs P0753, P0758 and P1860 are not present, go to next step. If DTCs P0753, P0758 and P1860 are present, remove appropriate TCC PWM solenoid ignition feed circuit fuse and inspect fuse. See WIRING DIAGRAMS . Replace fuse if necessary, and check for short to ground in wiring harness between transmission 20-pin connector and fuse. Repair wiring as necessary, then go to step 10). If fuse is okay, check for open in wiring harness between transmission 20-way connector and fuse. Repair wire as necessary, then go to step 10).
  3. Turn ignition off. Disconnect transmission 20-pin connector. Install Jumper Harness (J-39775) to VCM side of transmission 20-pin connector. Connect test light between ground and TCC PWM solenoid ignition feed circuit (terminal "E") at transmission 20-pin connector. See Figure. Turn ignition switch to ON position. DO NOT start engine.
  4. If test light does not light, check for open or high resistance in ignition feed circuit of TCC PWM solenoid. Repair as necessary, then go to step 10). If test light lights, connect test light between TCC PWM solenoid ground circuit and ignition feed circuit (terminals "E" and "S") at transmission 20-pin connector. Using scan tool, command TCC PWM solenoid on and off 3 times.
  5. If test light cycles on and off, go to next step. If test light does not cycle on and off 3 times, check TCC PWM solenoid ground circuit for open or short to ground. Repair circuit as necessary, then go to step 10). If circuit is okay, inspect wiring for poor connections at VCM connector. Check for bent, backed out, deformed or damaged terminals. Repair as necessary, then go to step 10). If connections and terminals are okay, replace VCM, then go to step 10).
  6. Turn ignition off. Disconnect jumper harness from VCM side of transmission 20-pin connector and install harness to transmission side of 20-pin connector. Connect a DVOM between TCC PWM solenoid ground circuit and ignition feed circuit (terminals "E" and "S") at transmission 20-pin connector.
  7. If resistance is 10-15 ohms, go to next step. If resistance is not10-15 ohms, disconnect TCC PWM solenoid connector. Measure resistance between TCC PWM solenoid terminals. If resistance is 10-15 ohms, check for open circuit in transmission wiring harness. Repair as necessary, then go to step 10). If resistance is not 10-15 ohms, replace TCC PWM solenoid, then go to step 10).
  8. Turn ignition off. Connect a DVOM between ground and TCC PWM solenoid ground circuit, and between ground and TCC PWM solenoid ignition feed circuit (terminals "E" and "S") at transmission 20-pin connector. If resistance at both terminals is more than 250 k/ohms, see DIAGNOSTIC AIDS. If resistance at both terminals is less than 250k/ohms, go to next step.
  9. Disconnect TCC PWM solenoid connector. Measure resistance between ground and each solenoid terminal. If resistance is more than 250 k/ohms, check for short to ground in transmission wiring harness. Repair as necessary, then go to next step. If resistance is less than 250 k/ohms, replace TCC PWM solenoid, then go to next step.
  10. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Test drive vehicle. Ensure voltage decreases to zero when TCC PWM solenoid is commanded on, and voltage increases to battery voltage when commanded off. Conditions must be met for 5 seconds. Select "Specific DTC" and enter DTC "P1860". If DTC P1860 is not present, repair is complete. If DTC P1860 is still present, repeat test.
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