Refer to Engine Controls Schematics
PCM Power, Grounding, MIL and DLC
.
Circuit Description
There should always be a malfunction indicator lamp (MIL) when the ignition is ON and the engine is OFF. Battery ignition voltage is supplied to the lamp. The PCM will turn the lamp ON by grounding the ignition feed circuit.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies if the problem is in the scan tool or the vehicle.
-
This step will check the ground circuits at the DLC connector.
-
The step will check for the battery and ignition feeds to the PCM.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Does the scan tool power-up? | -- | |||
3 |
Does the engine start then stall? | -- | ||
4 | Did the engine just crank over and not start? | -- | ||
5 |
Does the test lamp illuminate? | -- | ||
Probe the DLC terminals 4 and 5 using an unpowered test lamp connected to B+. Does the test lamp illuminate on both circuits? | -- | |||
7 |
Is the action complete? | -- | -- | |
8 | Repair the open ground circuit to the DLC terminals 4 and 5. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
Does the test lamp illuminate on each circuit? | -- | |||
10 | Measure the resistance between the battery ground and the PCM ground circuits in the PCM harness connectors using a DMM. Does the DMM display the specified value (or lower) on each circuit? | 5 ohms | ||
11 | Inspect the PCM for proper connections. Refer to Wiring Repairs in Wiring Systems. Did you perform a repair? | -- | ||
12 |
Important: The new PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | |
13 | Repair the Class 2 circuit for being open between the splice and the DLC. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
14 | Repair the circuit that did not illuminate the test lamp. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
15 | Repair the PCM ground circuits. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
16 | Repair the B+ supply circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- |
