P0885 TCM power relay control circuit/open

Content

P0885 – OBD-II Trouble Code Technical Description
What does trouble code P0885 mean?
Possible reasons
What are the symptoms of trouble code P0885?
How to diagnose trouble code P0885?
- Diagnostic errors
How serious is trouble code P0885?
What repairs will resolve the P0885 code?
P0885 – Brand Specific Information

P0885 – OBD-II Trouble Code Technical Description

TCM Power Relay Control Circuit/Open

What does the fault code mean P0885?

Every time you turn the ignition on, the TCM performs a self-test to ensure there is enough battery voltage to power it. Otherwise, DTC P0885 will be stored.

This Diagnostic Trouble Code (DTC) is a generic transmission code and applies to many OBD-II equipped vehicles (1996 and later). Although general, the exact repair steps may vary depending on the year, make, model, and transmission configuration.

If your vehicle stores a code P0885 accompanied by a malfunction indicator lamp (MIL), it means that the powertrain control module (PCM) has detected an open voltage or an undefined condition in the TCM power relay control circuit.

CAN is a complex system of wiring and connectors that is used to transmit data between the TCM and PCM. Data (including stored codes) can also be transferred to other controllers via CAN. Transmission input and output speed (RPM), vehicle speed and wheel speed are distributed among multiple controllers.

This code is unique in that it usually only stays if other codes related to the traction control system are present. Electronic transmission control systems in OBD-II equipped vehicles are controlled by a network of computers (called control modules). This involves constant communication between the different control modules via a controller area network (CAN).

The TCM power relay control circuit typically consists of a fuse and/or fuse link. A relay is used to initiate a smooth transfer of voltage to the corresponding component without the danger of a voltage surge.

The PCM performs a self-test every time the ignition is turned on. If there is no acceptable TCM power relay control voltage signal (battery voltage), a P0885 code will be stored and the MIL may illuminate.

Possible reasons

Reasons for this code may include:

The fuse has blown or rusted
Fuse link burned out
TCM power relay circuit shorted or open
Bad TCM/PCM or programming error
Broken or corroded connectors
Shorted wiring
Problem with ECU programming/function

What are the symptoms of a fault code? P0885?

Symptoms of a P0885 trouble code may include:

Electronic traction control disabled
Erratic gear shift pattern
Shift fault
Other related codes: ABS disabled

How to diagnose a fault code P0885?

Some of the tools needed to successfully diagnose P0885 include a diagnostic scan tool, a digital volt/ohm meter (DVOM), and a reliable source of vehicle information (All Data DIY).

Checking all system wiring and connectors and checking all system fuses and fuses is a good starting point for diagnosis. Use DVOM (voltage setting) to complete the previous task. If all fuses and fuses are OK and there is no battery voltage at the TCM power relay connector, you can suspect an open (or open) circuit between the appropriate fuse/fuse link and the TCM power relay.

Once you are sure that the TCM power relay has voltage at the appropriate terminals, you can test it by swapping the same relays. After diagnosis, you will need to clear the codes and test drive the vehicle to ensure that the P0885 code has cleared.

To accurately diagnose a P0885 code, you will need a diagnostic scan tool, a digital volt/ohm meter (DVOM), and a source of reliable vehicle information. Check all system wiring and connectors for damage, corrosion, and broken contacts. If voltage is present at the TCM power relay connector, the problem may be with the ECU or its programming. If there is no voltage, there is an open circuit between the ECU and the TCM. The P0885 code usually persists due to a faulty contact relay, a blown fuse link, or a blown fuse.

Diagnostic errors

Common mistakes when diagnosing the P0885 trouble code include incompletely checking electrical circuits, not checking fuses and fuses sufficiently, and ignoring possible ECU software problems. The error may also be insufficient checking of associated fault codes, which may affect the correct diagnosis.

How serious is the fault code? P0885?

Trouble code P0885 indicates problems with the transmission control module (TCM) power relay control circuit. Although this can cause various problems with shifting and other systems, in general it is not a critical emergency. However, ignoring it can lead to deterioration in the performance of the transmission and other vehicle systems, so it is recommended to immediately begin diagnostics and repairs.

What repair will help eliminate the code? P0885?

Trouble code P0885, which is related to problems in the TCM power relay control circuit, can be resolved by the following measures:

Replacement or repair of damaged wires and connectors in the control circuit.
Replace blown fuses or fuses if they are the source of the problem.
Replace or reprogram the transmission control module (TCM) if the problem is with the module itself.
Check and, if necessary, replace the TCM power relay if it is not functioning properly.
Monitor and resolve any other related issues such as power system faults or software errors.

Depending on the specific cause of the P0885 code, more detailed diagnostics and specialized repair procedures may be required. You should consider your vehicle's make and model to best understand what repair and diagnostic steps will be most effective.

What is P0885 Engine Code [Quick Guide]