Circuit Description
The PCM controlled starter system consists of the following components:
| • | The ignition switch |
| • | The Crank Request circuit |
| • | The PCM |
| • | Internal mode switch (Transaxle Range / P/N) Input |
| • | The crank relay |
| • | The starter solenoid |
The PCM uses the starter relay to control the operation of the starter. With the ignition switch in the crank position, the PCM receives system voltage on the Crank Request circuit. When the PCM senses the Crank Request input, the PCM checks that the right conditions exist to allow the operation of the starter. If the right conditions exist, the PCM turns ON the relay coil by applying ground to the control circuit. With the coil turned ON, the relay contacts close to apply voltage to the starter solenoid. As long as NONE of the following conditions are present, the PCM will allow the operation of the starter:
| • | The engine is running. |
| • | The PCM does not receive a correct vehicle theft deterrent (VTD) password from the VTD system. |
| • | The vehicle operator attempts to crank the engine for an extended length of time. |
| • | The internal mode switch input indicates that the transaxle is not in PARK or NEUTRAL. |
Diagnostic Aids
This diagnostic is intended to diagnose malfunctions in the non-PCM controlled portion of the starting system. To diagnose the PCM controlled portion of the system, refer to DTC P0615 Starter Relay Control Circuit .
Ignition system DTCs set with the ignition switch in the START position if the starter relay or the starter is inoperative. When the PCM enables starter operation, the PCM also initiates the diagnostic test routines for DTCs P0335, P0340, and P0385. If a condition exists which prevents the engine from cranking, the PCM will not receive signal input from the CKP and/or the CMP sensors, and the DTCs will set.
Check for the following conditions:
| • | The condition of the battery. |
| The vehicle battery should be fully charged and load tested before proceeding with the starter diagnosis. If, during cranking, the battery voltage falls too low, a PCM reset will occur. The PCM will disable starter operation for the rest of the ignition cycle. |
| • | Poor connections at the following areas: |
| Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
| • | The PCM |
| • | The starter relay |
| • | The starter assembly |
| • | The transaxle connector |
| • | Ignition switch |
| • | Damaged harness. |
| Inspect the wiring harnesses and harness connectors for damage. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. |
Relay Terminal Identification
Use the Underhood Fuse Block Assembly and/or the Rear Fuse Block Assembly details, located in the Engine Controls Components Views, to determine the correct cavities to probe during diagnosis. Four blade relays can be inserted two ways. The number designations (i.e. 30, 85, 86, 87, and 87a) displayed in the relay details correspond directly to the cavity and NOT the numbering on the relay.
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | |||||||||
2 |
Important: Check the battery connections. Fully charge and load test the battery before proceeding with starter diagnosis. Refer to Battery Load Test in Engine Electrical.Observe the IMS display on the scan tool. Refer to Scan Tool Data List in 4T80E - Automatic Transaxle. Does the IMS indicate PARK or NEUTRAL? | -- | Go to Step 3 | Go to Transmission Internal Mode Switch Logic in 4T80E - Automatic Transaxle | ||||||||
3 | Are any Transaxle DTCs set? | -- | Go to the applicable DTC. Go to Diagnostic Trouble Code (DTC) List/Type in 4T80-E Automatic Transaxle | Go to Step 4 | ||||||||
4 | Are any of the following Powertrain DTCs set?
| -- | Go to the applicable DTC. Go to Diagnostic Trouble Code (DTC) List/Type | Go to Step 5 | ||||||||
5 | Turn the ignition to start. Does the starter crank the engine? | -- | Go to Diagnostic Aids | Go to Step 8 | ||||||||
6 | With the ignition in the START position, observe the 12 volt reference display on the scan tool. Does the 12 volt reference display on the scan tool indicate OK? | -- | Go to Step 8 | Go to Step 7 | ||||||||
7 | Check the ignition 1 feed to the PCM for the following circuit conditions:
If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Important: If the ignition 1 feed is shorted to ground, replace the related fuse. Was a problem found? | -- | Go to Step 23 | Go to Step 22 | ||||||||
8 | With the ignition in the START position, observe the crank request display on the scan tool. Does the crank request display YES? | -- | Go to Step 12 | Go to Step 9 | ||||||||
9 |
Does the DMM display a voltage near the specified value? | B+ | Go to Step 10 | Go to Step 11 | ||||||||
10 | Check for poor terminal connections at the PCM. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Was a problem found? | -- | Go to Step 23 | Go to Step 22 | ||||||||
11 | Check for the following circuit conditions:
If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Was a problem found? | -- | Go to Step 23 | Go to Ignition Switch Diagnosis | ||||||||
12 |
Is the test lamp ON? | -- | Go to Diagnostic System Check - Engine Electrical in Engine Electrical | Go to Step 13 | ||||||||
13 | Check for a blown Starter Maxifuse. Is the fuse blown? | -- | Go to Step 14 | Go to Step 16 | ||||||||
14 |
Was a problem found? | -- | Go to Step 23 | Go to Step 15 | ||||||||
15 |
Was a problem found? | -- | Go to Step 23 | Go to Diagnostic System Check - Engine Electrical in Engine Electrical | ||||||||
16 |
Is the test lamp ON? | -- | Go to Step 17 | Go to Step 20 | ||||||||
17 |
Does the starter crank the engine? | -- | Go to Step 18 | Go to Step 19 | ||||||||
18 |
Was a problem found? | -- | Go to Step 23 | Go to Step 21 | ||||||||
19 |
Was a problem found? | -- | Go to Step 23 | Go to Diagnostic System Check - Engine Electrical in Engine Electrical | ||||||||
20 | Locate and repair the open starter solenoid battery positive feed to the start relay. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 23 | -- | ||||||||
21 | Replace the START relay. Is the action complete? | -- | Go to Step 23 | -- | ||||||||
22 |
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | Go to Step 23 | -- | ||||||||
23 | Turn the ignition to the START position. Does the starter crank the engine? | -- | System OK | Go to Step 3 |
