Diagnostic Aids

Perform this test when instructed during QUICK TEST or if directed by other test procedures. This test is used to diagnose the following:

• Thermostat
• Wiring Harness Circuits (THTRC & VPWR)
• Powertrain Control Module (PCM)

1. 10) DTC P1432: Check VPWR To Electronic Thermostat Harness Connector
   
   This DTC indicates PCM detected THTRC circuit voltage fell below a calibrated limit for a calibrated time during Comprehensive Component Monitor (CCM) test. Possible causes are:
   • THTRC Circuit Open Or Shorted To B+, Ground Or VPWR
   • VPWR Circuit Open
   • Open Or Shorted Thermostat Assembly
   • Faulty PCM

   Turn ignition switch to OFF position. Disconnect electronic thermostat connector. Turn ignition switch to ON position. Using a DVOM, measure voltage between ground and electronic thermostat harness connector VPWR terminal (Light Blue/Orange wire). If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in Light Blue/Orange wire between electronic thermostat and splice No. 153 at engine.

2. 11) Check Electronic Thermostat Resistance
   
   Turn ignition switch to OFF position. Using a DVOM, measure resistance between electronic thermostat connector terminals. Resistance should be 14-16 ohms. If resistance is within specification, go to next step. If resistance is not within specification, replace electronic thermostat.
3. 12) Check Thermostat Heater Control Circuit For Open In Harness
   
   Ensure ignition switch is turned to OFF position. Disconnect PCM connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM, measure resistance of THTRC circuit (Dark Blue wire) between electronic thermostat harness connector and PCM harness connector teminal No. 46. See Figure. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in THTRC circuit between electronic thermostat and PCM.
4. 13) Check THTRC Circuit For Short To GND Or VPWR In Harness
   
   Using a DVOM, measure resistance between PCM harness connector terminals No. 46 (THTRC) and No. 24, 25, 51, 76, 77, 91 (SIG RTN), 103 (PWR GND), 71 and 97 (VPWR). If all resistance measurements are more than 10 k/ohms and continuous memory DTC P1432 was retreived, go to TEST Z, step  1). If all resistance measurements are more than 10 k/ohms and KOEO or KOER DTC P1432 was retreived, replace PCM. If any resistance measurement is 10 k/ohms or less, repair THTRC circuit for short to GND, SIG RTN or VPWR circuit.