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VT Commodore Electrical Issues
Phoenix Mechanical

Starting Problems

1. As the battery, battery harness and starter motor age, cranking speeds can be greatly reduced. The most common issue (besides the battery) is the starter motor solenoid. The solenoid has a bakelite insulator where the cable poles connect, and through age and heat, the bakelite insulator becomes loose. They cannot be tightened, as they are crimped into the solenoid housing. A new solenoid/starter motor is usually required. Even after a new starter motor has been fitted, some cars still experience slow cranking speeds when the engine is warm. The main cause of this has been traced to excessive current draw from the battery harness (thanks to heat, and a once poorly operating starter). Once the battery harness has been replaced cranking speed is improved.

2. Some VT V8's (5.0ltrs) may not restart if the ignition switch has not been returned to the off position (like during a short stop where the key is not removed). Revised Memcals were introduced to eliminate this problem.

3. Some VT's that will not start, and have no fuel pressure, may have poor terminal connection on the fuel pump circuit inside the fuel sender unit assembly. A revised pump and sender unit assembly was introduced mid 2000

Gen III Pump and Sender unit assembly - Part number 25337050

4. Some early Gen III's suffer from poor or hard starting when warm, or the engine starts and runs rough for a few seconds. This may also be accompanied with harsh 1-2 and 2-3 auto shifts on light to medium throttle, and/or excessive driveline clunk noises from rear of vehicle during a 2-1 shift on closed throttle deceleration. A revised PCM calibration was introduced mid 2000 to overcome these issues.

5. Some VT V6's Automatics may suffer from cold start hesitation, poor engine response when cold, or a stall condition. Revised Memcals were introduced early 1999.

Memcal VT V6 Auto - Part number 16262780 (CXWB)

Memcal VT V6 Auto LPG - Part number 16262785 (CXWJ)

Memcal VT V6 SC Auto - Part number 16262784  (CXWH)

6. Some VT's had a problem with the ignition barrel intermittently jamming in the start or on position. This may lead to starter motor failure, or a situation where the ignition cannot be turned off. There is a pin and spring within the ignition barrel that can become misaligned. This can cause the barrel to become jammed. The pin and spring are carried on from previous models, and are not required in VT's.

7. VT V6's with factory LPG may sometimes be difficult to start. A revised Memcal was introduced early 1999.

VT V6 Auto LPG memcal - Part number 16262785 (CXWJ)

8. Some VT's may have starting issues caused by a defective Fuel Pump relay (or have no low beam headlights, as the Low Beam relay is the same as the fuel pump relay). A revised relay was introduced late 2000. In case of starting or headlamp problems, the old relay (92047112) should not be used.

Relay - Part number 92107897

9. Some starting issues can be cause by the BCM (Body Control Module). The BCM may electronically lock up or freeze (caused by voltage spikes), which may restrict starting, locking and unlocking etc. Some BCM's were returned under warranty because of these issues. In some situations, the key reader circuit ban be a potential source of a voltage spike, and a grounding patch harness was released to reduce this occurrance.

VTII Body Control Module Mid Series - Part number 92145251

VTII Body Control Module Low Series - Part number 92145250

Remote Key Readers - Some remote key readers have poor range, especially on hot days. The average working range is within 4 metres. To cope with high ambient temperatures, the remote receiver's circuit boards have been upgraded with higher tolerance capacitors from 28/08/2001.

All VT and VU Receiver Remote Key - Part Number 92051734

WH Receiver/Sun Sensor Remote Key - Part number 92050898

Alternator - Some VT's can suffer from alternator failure, which is caused by excessive current flow. This can also damage the positive alternator cable that runs to the battery. Battery to alternator wiring was revised in mid 1998 to help reduce this problem. Patch harnesses are available.

V6 patch harness - Part number 92075373

V8 patch harness - Part number 92077126

Battery harness kit - Part number 92142111

Gauges inoperative - Some VT executives have gauge cluster "lock-up", where the tacho, speedo, gauges and some or all of the LCD readout does not work. Apparently, static electricity discharge (due to clothing or temperature) can be the cause. The top frame and cushion assembly is mounted to the seat frame with nylon bushes, which act as an insulator. An earth lead connected between the top part of the drivers seat and the base is advised.

Instrument warning lamps (ABS) - The ABS module consists of 2 main parts. A hydraulic unit and an electrical unit. The most common failure seen with the module is when the ABS Electronic module fails. This often results in a myriad of dash lights being illuminated, not just the ABS light. When the ABS Electronic module fails, it can also interrupt scanning procedures for the ABS, BCM (Body Control Module) and PCM (Powertrain Control Module).

Another cause can be water entry into the engine harness connection area, under the bonnet, against the right strut tower. Apparently, water gets onto and through the "horse-shoe" shaped plastic wiring support, which eventually tracks down to the ABS connector, causing all sorts of warning lamp issues. Foam fillers and sealants are used to help reduce the amount of water that can get through to these areas.

Indicator Switch - Some VT turn signal lamps will not work during cold temperatures. A possible cause for this can be the hazard lamp switch. If the hazard switch becomes slightly dislodged from the dash fascia, the locking tab of the hazard switch can distort the switch case. This can interrupt the signal from the indicator switch to the indicator lamps. Revised hazard switches were introduced late 1999.

Side Air Bags - In some situations, the side air bag container may distort, which can damage the airbag's electrical connector. This may eventually cause the air bag light on the dash to illuminate. Revised side air bag assemblies where introduced mid 1999.

Fuel Gauge calibration - Some early VT's will not read full on the fuel gauge, even though the tank is full. In mid 1997, the calibration was changed in production. The fuel gauge calibration can be changed by Holdens, using a Tech 2 (Holden Scan Tool).

Heater Fan Failure - Some early VT's had a problem with excessive current draw from the heater fan, which caused the fan motor resistor to fail. A revised heater fan was introduced in mid 1998. Apparently, vehicles fitted with a small solid state fan resistor (VS22445) will need a larger solid state fan resistor (92141495) if the heater fan is inoperative. If the vehicle has the larger solid state fan resistor fitted (92141495), and the heater fan fails, a revised heater fan (92142044) should be used.

Interior Light - There have been cases of the interior light or door courtesy lights remaining on when the doors are closed. Apparently the cause is one of the rear door light switch wires have been pinched by the front door latch attaching screw, which is fitted after the switches.

GEN III O2 Sensors - Some Gen III Automatics will experience water contamination on the LH O2 sensor plug, which can cause O2 sensor faults. This problem may be a result of the A/C drain tube in the transmission tunnel, as it is in the same proximity as the O2 sensor harness. A bracket was introduced for the O2 sensor connector that will position it away from the A/C drain tube.

O2 Sensor Connector Mounting Kit – Part number 92145044

O2 sensor LH - Part number 25326439

GEN III Cam Position Sensor - Early Gen III Cam Position Sensors may separate internally, which may result in the check engine lamp being illuminated, the engine is unable to be started, or excessive cranking is required to start the engine. Sensors manufactured before 9/1999 should not be used.

Camshaft Position Sensor - Part number 12561211 or 12560228

GEN III Knock sensors - Some Gen III's knock sensor calibrations (in the PCM) are over sensitive, and may set a fault code without a valid reason. Revised software was implemented late 1999.

Wiper mechanism - VT wiper arm mechanisms commonly break at the right mounting bracket below the front windscreen. This sometimes results in the wiper arm hitting and cracking the front windscreen. Wiper mechanisms are available from Holdens or motor wreckers.

Wagon Rear Wiper motor - Some rear wipers will not operate because the internal linkages jam up. This can also damage the wiper motor. A revised wiper motor and linkage assembly was introduced mid 2000.

Rear Wiper Motor Assembly - Part number 92103204

Electrical malfunctions - VT Commodores use a BCM (Body Control Module). This module is responsible for electrical operation of components inside the vehicle, and is also responsible for the vehicle alarm, and keyless entry systems. The BCM is separate from the PCM (Powertrain Control Module aka Engine Computer). The BCM controls most power systems, such as central locking, electric windows, power antennas, window demisting and cruise control. If this module becomes faulty through a spike voltage, or an accident, any, or all of the above mentioned power systems may become inoperative. Depending on the Vehicle type, a new body control module will come with a new alarm remote. Some types are supplied without an alarm remote, and in this case, a new remote will be needed, and the car will need to be booked in for a tech 2, to reprogram the remote to the body control module.

One area of concern for possible intermittent electrical issues is the wiring harness at the LH rear of the engine compartment. In some VT's this can rub on the body of the theft deterrent horn. The condition has the potential to cause numerous intermittent faults, depending on which wire is damaged.

Some BCM's may suffer from water damage. The retaining bolt in the Right side of the Fire wall panel may be insufficiently sealed. If water leaks past this bolt, connector D of the BCM can be affected. The firewall retaining bolt should be checked for tightness, and resealed with a sealer such as silicone RTV 732 (92140051).

Central locking - On odd occasions, The keyless entry system will lock the doors, the alarm horn sounds, and then the doors unlock. The most common cause (besides a faulty solenoid, that stops working all together) is a sticking inner door lock button, which will stop one door from locking. The BCM recognizes this and unlocks all doors until the problem is rectified. In the short term, manually locking the offending button/door, usually allows the car to be securely locked. Replacing the door lock button (or usually just the orange nib) will usually overcome the problem.

I have had several situations that had total failure. All doors were on deadlock, but the driver's door could be unlocked manually with the key. No other door or door lock could be opened or manipulated. After dismantling each door from the inside and removing the central locking solenoids, the doors could be opened. All the solenoids had jammed/locked into the deadlock position. All 4 solenoids where replaced. Apparently, water leaking in through the bottom of door trims, or water not draining from the doors can sometimes upset the central locking wiring and solenoids in the door.

PS; If your remote key fob breaks, don't drill a hole through it for your key ring, as the circuit board inside doesn't like it. Don't laugh, I've seen it done!