Circuit Description
The PCM uses the 5 Volt Reference A circuit as a sensor feed to the following sensors:
| • | The MAP sensor. |
| • | The EGR Valve Pintle Position sensor. |
The PCM monitors the voltage on the 5 Volt Reference A circuit. If the voltage is out of tolerance, the PCM will set DTC P1635.
Conditions for Setting the DTC
The engine is running.
Conditions for Setting the DTC
| • | The PCM detects a voltage out of tolerance condition on the 5 Volt Reference A circuit. |
| • | The above condition is present for longer than 10 seconds. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed. |
| • | The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using the scan tool. |
Diagnostic Aids
Important:: Be sure to inspect PCM and engine grounds for being secure and clean.
Check for the following conditions:
| • | Poor connection at PCM - Inspect harness connectors for the following items: |
| - | Backed out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed or damaged terminals |
| - | Poor terminal to wire connections |
| • | Damaged harness - Inspect the wiring harness for damage. |
| • | If the harness appears to be OK, observe the MAP display on the scan tool with the ignition ON, engine not running while moving connectors and wiring harnesses related to the following sensors. A change in the MAP display will indicate the location of the fault. |
| - | The MAP sensor |
| - | The EGR valve |
Review the Freeze Frame/Fail Records vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
2 |
Does the voltage measure more than the specified value? | 5.1 V | ||
3 |
Does the test lamp illuminate? | -- | Go to Diagnostic Aids | |
Does the voltage measure more than the specified value? | 5.1 V | |||
5 |
Does the test lamp illuminate? | -- | ||
6 |
Does the voltage measure more than the specified value? | 0.0 V | ||
7 |
Does the test lamp illuminate? | -- | ||
8 | Repair the short to voltage on the 5 volt reference circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | -- | |
9 | Repair the short to ground on the 5 volt reference circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | -- | |
10 | Repair the short to voltage on the appropriate sensor signal circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | -- | |
11 | Repair the short to ground on the appropriate sensor signal circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | -- | |
12 |
Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Did you complete the replacement? | -- | -- | |
13 |
Does the DTC reset? | -- | ||
14 | Does the scan tool indicate any DTCs set that you have not diagnosed? | -- | Go to applicable DTC table | System OK |
