Circuit Description
The PCM controlled starter system consists of the following components:
| • | The Ignition switch |
| • | The Crank Request circuit |
| • | The PCM |
| • | The Crank relay |
| • | The Transaxle Range switch |
| • | The Starter solenoid |
When the Ignition switch is turned to the Crank position, B+ is sent to the PCM via the Crank Request circuit. The PCM has the ability to disallow starter operation if conditions inappropriate for starter operation exist. The PCM will disable the starter under the following conditions:
| • | The engine is running |
| • | A correct VTD password is not received from the BCM |
| • | The vehicle operator continues to engage the starter for an extended period of time |
If no inhibiting conditions are present, and the PCM detects voltage on the Crank Request circuit, the PCM grounds the Crank Relay Control circuit. Current from the Crank maxifuse flows through the relay through the Transaxle Range switch (only in P/N) to the Starter solenoid.
Diagnostic Aids
This diagnostic procedure is intended to identify electrical malfunctions within the PCM controlled portion of the starting system. For additional system diagnosis, refer to Starting System Check in Electrical Diagnosis.
Use the Connector Test Adapter Kit J 35616 for any test that requires probing the PCM harness connectors, electrical center fuse/relay cavities, component terminals or a component harness connector. Using this kit will prevent damage caused by improper probing of connector terminals.
If the problem is intermittent, refer to Intermittent Conditions for diagnosis.
Test Description
The numbers below refer to numbers on the diagnostic table.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the PCM Controlled Starter Functional Check? | -- | Go to Powertrain Control Module Controlled Starter Diagnosis | |||||||||
Monitor Crank Request using a scan tool. Does the scan tool indicate No with the key in the On position and Yes with the key in the Start position? | -- | Refer to Diagnostic Aids. | ||||||||||
3 | Does the scan tool always indicate Crank Request No? | -- | ||||||||||
4 | Check the Crank fuse. Is the fuse OK? | -- | ||||||||||
5 |
Does the DMM display near the specified value with the key in the Start position? | B+ | ||||||||||
6 |
Does the DMM display near the specified value with the key in the Start position? | B+ | ||||||||||
7 | Check for the following conditions and repair as necessary:
Refer to Intermittents and Poor Connections Diagnosis . Is the action complete? | -- | -- | |||||||||
8 |
Does the DMM display near the specified value with the key in the On position? | B+ | ||||||||||
9 |
Is voltage indicated? | -- | ||||||||||
10 | Check for continuity between the Crank Request circuit and the following other circuits in the Ignition switch harness connector:
Is continuity indicated? | -- | ||||||||||
11 | Repair the open/high resistance Crank Request circuit. Is the action complete? | -- | -- | |||||||||
12 | Check for the following conditions and repair as neccessary:
Is the action complete? | -- | -- | |||||||||
13 | Repair the Crank Request circuit shorted to power. Is the action complete? | -- | -- | |||||||||
14 | Repair the circuits that are shorted together. Is the action complete? | -- | -- | |||||||||
15 | Check for poor connections/terminal tension at the Ignition switch. Refer to Intermittents and Poor Connections Diagnosis Was a problem found and corrected? | -- | ||||||||||
16 | Replace the Ignition switch. Is the action complete? | -- | -- | |||||||||
17 | Check for poor connections/terminal tension at the PCM. Refer to Intermittents and Poor Connections Diagnosis Was a problem found and corrected? | -- | ||||||||||
18 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming Is the action complete? | -- | -- | |||||||||
19 | Monitor Crank Request using a scan tool. Does the scan tool indicate No with the key in the On position and Yes with the key in the Start position? | -- | System OK |
