The powertrain control module (PCM) provides a 5-volt reference to the following sensors:
• | The throttle position (TP) sensor 1 |
• | The accelerator pedal position (APP) sensor 2 |
• | The engine cooling fan speed sensor |
• | The air conditioning (A/C) refrigerant pressure sensor |
• | The fuel tank pressure (FTP) sensor |
• | The oil pressure sensor (OPS) |
The PCM monitors voltage on the 5-volt reference circuit. If the voltage is higher or lower than required, DTC P1635 will set.
The ignition is ON.
• | The PCM detects a voltage that is higher or lower than required on the 5-volt reference circuit. |
• | The above condition is present for longer than 10 seconds. |
• | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
• | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records. |
• | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
• | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
• | Clear the MIL and the DTC with a scan tool. |
Step | Action | Values | Yes | No | ||||
---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||
2 |
Important: If the vehicle has a cranks but will not run condition proceed to step 3. Does the DTC fail this ignition? | -- | Go to Step 3 | Go to Intermittent Conditions | ||||
3 |
Is the voltage near the specified value? | 5 V | Go to Step 5 | Go to Step 4 | ||||
4 | Is the voltage more than the specified value? | 5 V | Go to Step 8 | Go to Step 6 | ||||
5 |
Is the voltage near the specified value? | 5 V | Go to Step 10 | Go to Step 9 | ||||
6 |
Was a component replaced? | -- | Go to Step 12 | Go to Step 7 | ||||
7 |
Did you find and correct a condition? | -- | Go to Step 12 | Go to Step 10 | ||||
8 |
Did you find and correct a condition? | -- | Go to Step 12 | Go to Step 10 | ||||
9 | Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||
10 | Test this 5-volt reference circuit for a short to the TAC motor control 1 or 2 circuits. Did you find and correct a condition? | -- | Go to Step 12 | Go to Step 11 | ||||
11 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||
12 |
Does the DTC run and pass? | -- | Go to Step 13 | Go to Step 2 | ||||
13 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK |