Dec 032014
 

Introduction…

A customers 2007 Toyota Aurion was towed into the workshop after the NRMA diagnosed its 6 speed U660E Automatic Transmission as being lock in Fail Safe mode.  When a Fail Safe condition presents it self the vehicles transmission is placed into a safe condition in the event of a breakdown or malfunction. The engine light or transmission related selector lights may also flash relating to a Code present in either the ECU (Engine Control Unit) or TCM (Transmission Control Unit).

 Diagnoses…

The vehicle presented a constant engine light on the dash so with a diagnostic tool we scanned the ECU module and found the following hard code (A hard code either won’t clear or returns immediately after clearing).

DTC U0101 Lost Communication with Transmission Control Module (TCM).

We then tried to scan the TCM but our scanner would not communicate at all so we tried some other modules to make sure the scanner was compatible with the vehicle.  The other basic modules showed no trouble codes so then we checked for blown fuses.

Fuses – The main fuse box is located in the engine bay and we tested them all and found none where faulty.

Toyota Aurion U660 Transmission Control Module

TCM located on the Transmission.

Power – Next we checked the power at the TCM (Located on the Transmission see image) plug which will need the ignition turned on which was also fine.

Communication – With high speed data traveling between the TCM and the ECU at a great speed any interruption can stop the system so next we disconnected the plugs on the ECU and cleaned them as well as the TCM. We also preformed a hard reset buy disconnecting the battery and discharging any memory in the system. With everything reconnected the fault still remained so it was looking like a faulty module or bad wiring.

Wiring – We knew the module had power but was it sending any signals? an easy check is to probe a CAN-Bus line with a multimeter. Most Can-Bus systems use a low to high volt signal to transmit data on the network if you have anywhere around 3- 5 volts as a guide there is communication on the network. When we probed the TCM there was only 1 volt showing which means there is really no activity from the TCM.

The Problem…

The fault pointed to a faulty/dead Transmission Control Module as the U0101 code suggested so we decided to try a second hand unit. A new one from the dealer was about 4 times the price and not available for a few days.

The Fix…

Replace the TCM with a second had unit which immediately removed the engine light and allowed us to clear the previous hard code in the ECU.

Conclusion…

Although we did not find any reason for the TCM to have failed it could be for a number of unknown reasons. Due to it being located on the transmission vibration, heat, water, oil or acid from the battery could have played apart.

See Also…




Feb 072014
 

Toyota KLUGER & HIGHLANDER P0500 Vehicle Speed Sensor (VSS) Malfunction Code Introduction…

Tracking down sensor problems are normally straight forward with scan tools and workshop manuals. So when pulled out a P0500 in a customers Toyota Kluger we went straight for the speed sensor on the front diff housing but thats where things got interesting. Now any other car you would look straight to the diff housing of the transmission but there is no sensor its just blanked.  So how does the vehicle get its vehicle speed for the instrument cluster and ECM?

The Sensor & Signals…

The Anti-Lock Brake System (ABS) wheel speed sensors detect wheel speed and sends the signals to ABS ECU. The ABS ECU converts the signals into a 4-pulse signal and outputs the signal to the instrument cluster.  The Instrument cluster converts the signal to a more precise waveform and outputs the signal to ECM. ECM determines the vehicle speed based on the frequency of these pulse signals.

Codes Set…

DTC is set when ECM does not detect any Vehicle Speed Sensor (VSS) signal while the vehicle is in motion.

Code…

DTC P0500: VEHICLE SPEED SENSOR (VSS) MALFUNCTION (ES 300 & HIGHLANDER)

Possible Causes…

  • Faulty wheel speed sensors.
  • Open or short in VSS circuit.
  • Faulty instrument cluster.
  • Faulty ECM.

Diagnosis & Repair…

Toyota ECU Replacement for P0500 Code Kluger and Highlander

Toyota ECU Replacement for P0500 Code Kluger and Highlander

  1. Test drive vehicle and check operation of speedometer. If speedometer is not operating correctly, repair speedometer as necessary. If speedometer is operating correctly, go to next step.
  2. Raise and support front of vehicle. Shift transmission into Neutral. Access ECM behind glove box. Using DVOM, backprobe terminal No. 22 at appropriate ECM connector. Turn ignition on. Slowly rotate a drive wheel while observing voltage on DVOM. Voltage should fluctuate from zero volts to 4.5-5.5 volts as wheel is turned. If voltage is not as specified, locate and repair open/short circuit between terminal No. 22 at ECM harness connector and appropriate instrument cluster connector. If voltage is as specified, go to next step.
  3. Check for loose or poor connection at ECM connector E8. Repair as necessary. If connection is okay, replace ECM and retest system.

CAUTION…

If ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system.

Diagnostic Aids…

Using a scan tool, read freeze frame data. Freeze frame records will indicate engine conditions when malfunction is detected.

Affected Vehicles/Transmissions…

2001-2013 Toyota Highlander  AUTOMATIC TRANSMISSIONS U140E (FWD), U140F (AWD), U241E (FWD) & U151F (AWD)

2001-2013 Toyota Kluger AUTOMATIC TRANSMISSIONS U140E (FWD), U140F (AWD), U151E (FWD) & U151F (AWD)

2001-2006 Lexus ES 300 AUTOMATIC TRANSMISSIONS  U151E (FWD)

See also…
Changing ECM
Programing ECM
Servicing Automatic Transmission
List of Toyota Transmission