Service Information: Diagnostics

All diagnostics of the ECVT are carried out via the EMS. Using DISplus, the EMS can request actions from the GIU and monitor these actions for the correct performance.

A requirement has been identified for the GIU to perform an integrity check on its output drives. This mode will be engaged as part of the end of line testing during production, and also for the technician performing diagnostic testing. In response to these signals, the GIU shall perform the following:

Perform a test on the LED drives.
Test both the clutch and pressure solenoids.
Attempt to move the motor through a complete cycle.

Once the operation of the EMS 2000 has been established, the GIU operation should be established. The CAN link between the GIU and the EMS 2000 can be verified by observing the LCD display in the instrument cluster. The display should change in accordance with the gear lever selector and is an indication that the selector switches are operational and the drive from the EMS 2000 to the instrument cluster is operational.

If the ratio control motor is suspected to be faulty the following procedure can be carried out to confirm its state:

Turn the ignition off and wait 5 minutes for the EMS 2000 to power down.
Unplug the connector from the GIU and using a multi-meter measure phase coils across pin 5 & 6 and then 7 & 8. The reading should be between 18-30 Ohms.
When a reading cannot be obtained, try reading the phase coils on the transmission connections by probing the connection directly on the transmission.
When readings can not be obtained at the transmission, the motor is assumed to be faulty.

PROBLEM SYMPTOMS CHART

Fault/Symptom	Most Likely Causes
Transmission stays in highest ratio. Vehicle pulls away as normal, but engine speed does not rise as normal	Road speed sensor fault Road speed sensor interfrence Fault with EMS 2000 or Drive-by-wire system Ratio Control Motor fault
Vehicle pulls away and accelerates sluggishly	Transmission malfunction
Transmission stays in lowest ratio. Vechicle pulls away as normal, but engine speed rises rapidly to around 6000 rpm at 30 KPH	Sticking Primary valve Ratio Control Motor Fault Ratio Control Motor Wiring Transmission malfunction
Engine speed stuck at a constant speed for most driving conditions	Selector switch fault Selector cable fault Link lost between EMS 2000 and GIU Ratio Control Motor Fault Road Speed Sensor Fault
No Creep in D	Transmission is overheating Clutch solenoid fault GIU Fault Transmission Fault
High engine load in D	Open or Short Circuit LED drives GIU Fault Transmission Fault
No center console LEDs with ignition On	Open or Short Circuit LED drives GIU Fault EMS 2000 Main Relay fault (No power to GIU) Invalid Selector Position/Selector Fault