Circuit Description
The transmission control module (TCM) samples the voltage on the Ignition Accessory voltage circuit every 0.1 seconds. Lower than normal voltage may be inadequate to operate the transmission control solenoids properly. Improper solenoid operation may cause erratic transmission operation, which may result in internal damage.
If the TCM detects a low voltage on the Ignition Accessory voltage circuit, DTC P2536 sets. DTC P2536 is a type A DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2536 Ignition Accessory Switch Circuit
Conditions for Running the DTC
| • | No controller area network (CAN) DTC U2104 or U0100. |
| • | No engine speed DTC P0727. |
| • | The engine speed is 400 RPM or greater. |
| • | The ignition voltage is between 10.2 volts and 15.5 volts. |
| • | Trans. Protection Mode is OFF. |
Conditions for Setting the DTC
The TCM detects less than 8.68 volts on the Ignition Accessory voltage circuit for 20 seconds.
Action Taken When the DTC Sets
| • | The TCM requests the powertrain control module (PCM) to illuminate the malfunction indicator lamp (MIL). |
| • | The PCM records the operating conditions when the Condition for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records. |
| • | The TCM records the operating conditions when the Condition for Setting the DTC are met. The TCM stores this information as Failure Records. |
| • | The TCM stores DTC P2536 in TCM history. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request. |
| • | A scan tool can clear the MIL/DTC. |
| • | The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring. |
| • | The TCM cancels the DTC default actions when the fault no longer exists and the DTC passes. |
Step | Action | Yes | No |
|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Important: Before clearing the DTCs, use the scan tool in order to record the Failure Records for reference. Using the Clear Info function will erase the stored Failure Records from the transmission control module (TCM). Does DTC P2536 reset? | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections |
3 |
Did you find the condition? | Go to Step 4 | Go to Step 6 |
4 | Test the Ignition Accessory voltage circuit of the TCM for a short to ground between the underhood fuse block and the TCM. Refer to Testing for Short to Ground and Wiring Repairs . Did you find and correct the condition? | Go to Step 9 | Go to Step 5 |
5 | Test the Ignition Accessory voltage circuit of the TCM for a short to ground between the underhood fuse block I/P fuse block. Refer to Testing for Short to Ground and Wiring Repairs . Did you find and correct the condition? | Go to Step 9 | -- |
6 | Test the Ignition Accessory voltage circuit of the TCM for an open between the underhood fuse block and the TCM. Refer to Testing for Continuity and Wiring Repairs . Did you find and correct the condition? | Go to Step 9 | Go to Step 7 |
7 | Test the Ignition Accessory voltage circuit of the TCM for an open between the underhood fuse block and the I/P fuse block. Refer to Testing for Continuity and Wiring Repairs . Did you find and correct the condition? | Go to Step 9 | -- |
8 | Replace the TCM. Refer to Control Module References . Did you complete the replacement? | Go to Step 9 | -- |
9 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | Go to Step 10 | Go to Step 2 |
10 | With a scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | -- |
