The following technical tips provide repair information about specific conditions on a variety of vehicles. If you have a tough or unusual service repair, the TSS Technical Assistance Hot Line can help. Call 1-800-825-5886, prompt #2, to speak with a technical expert with the latest OEM information.
Manual Transmission Blocked Shift or Difficulty Shifting
2003-2007 Saturn ION, 2004-2007 Saturn VUE, 2005-2010 Chevrolet Cobalt, 2005-2009 Pontiac G5, and 2006-2010 Chevrolet HHR -- equipped with a Getrag manual transmission (RPO M86 or MG3)
The manual transmission may exhibit a hop-out or blocked shift of 1st, 3rd and 5th gears or difficulty shifting. The shift lever roll pin may back out and contact the shift cover during a shift event, which can cause an incomplete, blocked shift or difficulty shifting the transmission.
Prior to any internal transmission repairs, inspect the shift cover and lever to determine if the roll pin has backed out and is dragging on or contacting the housing. If roll pin contact is evident, then the shifting difficulty may not be an internal transmission condition. (Fig. 13)
If the shift cover shows witness marks from contact with the roll pin, replace the complete shift cover assembly. Do not replace the transmission for this condition.
If the roll pin is not dislodged, follow the appropriate Service Information diagnostics.
Driveline Noises in 4WD
2009 and prior Chevrolet and GMC light-duty trucks and SUVs equipped with 4WD, 2009 and prior HUMMER H2 and H3
These vehicles may exhibit a groan, growl, or moan noise when operating in 4WD Lock.
The noise may be due to a vibration that is heard or felt as a result of the front axle being excited to resonance at its natural frequency. This is a combination of the transfer case chain link frequency, engine firing frequency, tire circumference variation, and various other tolerances built into the 4WD system.
A groan, growl or moan noise on deceleration while in 4WD Lock is also the result of loading the transfer case chain, which is an operating characteristic. This is just one example of a transfer case link frequency as noted previously.
On certain models, such as 3/4 -and 1-ton vehicles, tire pressures can vary from front to rear based on the manufacturer's specifications. Refer to the vehicle's Tire Information Label for tire pressure specifications.
The difference in tire pressures affects the rolling tire circumference from front to rear, which can increase driveline noise while in 4WD.
For test purposes on vehicles with different tire pressures, drop the tire pressure in the rear to match the front. If the noise is reduced or eliminated, this confirms the difference in tire pressures from front to rear can affect the noise when operated in 4WD. Set the rear tire pressure back to the manufacturer's specification.
No repairs are recommended for this condition. For more information regarding driveline noises while in 4WD, refer to GM bulletin #01-04-18-001F.
Steering Wheel Vibration
1996-98 Ford Crown Victoria, Mercury Grand Marquis, Lincoln Town Car
A vibration or buzzing noise may be heard or felt in the steering wheel on right turns at engine RPMs between 590-1100. This condition may be caused by valve resonance and power steering pump pulsations.
Replace the power steering pressure hose to dampen the noise. A new power steering hose bracket is attached to a stud on the engine, between the crankshaft pulley and power steering pump pulley.
Also check the fluid level in the reservoir, verify there is no air in the power steering system, and make sure that the steering shaft does not contact any other lines or components.
Slipping Clutch Conditions
2004-09 GM passenger cars or light-duty trucks equipped with a gasoline engine and manual transmission
The Service Engine Soon (SES) light may illuminate and, using a scan tool, DTC P0502 (Vehicle Speed Sensor Circuit Low Voltage) may be found stored in the PCM.
If no cause for the DTC can be found after following the appropriate Service Information diagnostics, the condition may be customer induced.
Supporting data may be found in the freeze frame information stored with the DTC. Review the scan tool data parameters: Calculated Engine Load, Engine Speed, Output Shaft Speed Sensor and Clutch Pedal Position.
Inform the customer that excessive slipping of the clutch with the vehicle stationary or moving at low speeds may cause this DTC to set. This is considered normal vehicle operation.
No Power Steering Assist
Dodge Ram 2500
When replacing the power steering pump, properly torque the mounting bolts to specification during pump installation. Do not use an air ratchet.
This is a vane type power steering pump with the mounting bolts going through the housing. If the bolts are over-torqued, they may compress the front and rear cover against the vanes, leading to severe wear, metal debris in the system, and eventual pump failure.
Manual Transmission Blocked Shift or Difficulty Shifting
2003-2007 Saturn ION, 2004-2007 Saturn VUE, 2005-2010 Chevrolet Cobalt, 2005-2009 Pontiac G5, and 2006-2010 Chevrolet HHR -- equipped with a Getrag manual transmission (RPO M86 or MG3)
The manual transmission may exhibit a hop-out or blocked shift of 1st, 3rd and 5th gears or difficulty shifting. The shift lever roll pin may back out and contact the shift cover during a shift event, which can cause an incomplete, blocked shift or difficulty shifting the transmission.
Prior to any internal transmission repairs, inspect the shift cover and lever to determine if the roll pin has backed out and is dragging on or contacting the housing. If roll pin contact is evident, then the shifting difficulty may not be an internal transmission condition. (Fig. 13)
If the shift cover shows witness marks from contact with the roll pin, replace the complete shift cover assembly. Do not replace the transmission for this condition.
If the roll pin is not dislodged, follow the appropriate Service Information diagnostics.
Driveline Noises in 4WD
2009 and prior Chevrolet and GMC light-duty trucks and SUVs equipped with 4WD, 2009 and prior HUMMER H2 and H3
These vehicles may exhibit a groan, growl, or moan noise when operating in 4WD Lock.
The noise may be due to a vibration that is heard or felt as a result of the front axle being excited to resonance at its natural frequency. This is a combination of the transfer case chain link frequency, engine firing frequency, tire circumference variation, and various other tolerances built into the 4WD system.
A groan, growl or moan noise on deceleration while in 4WD Lock is also the result of loading the transfer case chain, which is an operating characteristic. This is just one example of a transfer case link frequency as noted previously.
On certain models, such as 3/4 -and 1-ton vehicles, tire pressures can vary from front to rear based on the manufacturer's specifications. Refer to the vehicle's Tire Information Label for tire pressure specifications.
The difference in tire pressures affects the rolling tire circumference from front to rear, which can increase driveline noise while in 4WD.
For test purposes on vehicles with different tire pressures, drop the tire pressure in the rear to match the front. If the noise is reduced or eliminated, this confirms the difference in tire pressures from front to rear can affect the noise when operated in 4WD. Set the rear tire pressure back to the manufacturer's specification.
No repairs are recommended for this condition. For more information regarding driveline noises while in 4WD, refer to GM bulletin #01-04-18-001F.
Steering Wheel Vibration
1996-98 Ford Crown Victoria, Mercury Grand Marquis, Lincoln Town Car
A vibration or buzzing noise may be heard or felt in the steering wheel on right turns at engine RPMs between 590-1100. This condition may be caused by valve resonance and power steering pump pulsations.
Replace the power steering pressure hose to dampen the noise. A new power steering hose bracket is attached to a stud on the engine, between the crankshaft pulley and power steering pump pulley.
Also check the fluid level in the reservoir, verify there is no air in the power steering system, and make sure that the steering shaft does not contact any other lines or components.
Slipping Clutch Conditions
2004-09 GM passenger cars or light-duty trucks equipped with a gasoline engine and manual transmission
The Service Engine Soon (SES) light may illuminate and, using a scan tool, DTC P0502 (Vehicle Speed Sensor Circuit Low Voltage) may be found stored in the PCM.
If no cause for the DTC can be found after following the appropriate Service Information diagnostics, the condition may be customer induced.
Supporting data may be found in the freeze frame information stored with the DTC. Review the scan tool data parameters: Calculated Engine Load, Engine Speed, Output Shaft Speed Sensor and Clutch Pedal Position.
Inform the customer that excessive slipping of the clutch with the vehicle stationary or moving at low speeds may cause this DTC to set. This is considered normal vehicle operation.
No Power Steering Assist
Dodge Ram 2500
When replacing the power steering pump, properly torque the mounting bolts to specification during pump installation. Do not use an air ratchet.
This is a vane type power steering pump with the mounting bolts going through the housing. If the bolts are over-torqued, they may compress the front and rear cover against the vanes, leading to severe wear, metal debris in the system, and eventual pump failure.
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