Pontiac Tech Tip: Grinding and/or Growling Noise in Park on Incline – UnderhoodService

Pontiac Tech Tip: Grinding and/or Growling Noise in Park on Incline

Owners of some vehicles equipped with Hydra-Matic front wheel drive transaxles may comment on a grinding and/or growling noise that is noticeable when standing in PARK on a hill or slope with the engine running and the parking brake not applied.

Affected Models:
2007 and prior Pontiac passenger cars and light trucks with Hydra-Matic front wheel drive (FWD) automatic transmissions.

Service Information:
Owners of some vehicles equipped with Hydra-Matic front wheel drive transaxles may comment on a grinding and/or growling noise that is noticeable when standing in PARK on a hill or slope with the engine running and the parking brake not applied. Under these conditions, the weight of the vehicle puts a load on the parking pawl which can create a “ground-out” path through the drive axles, front struts, springs and spring towers. Normal engine noise can be transmitted to the passenger compartment through the “ground-out” path.

Owners concerned about this condition should be advised to apply the parking brake prior to shifting into PARK. This is the recommended procedure described in the owner’s manual. Applying the parking brake first will put the load of the vehicle on the rear brakes rather than on the parking pawl.

Refer the owner to the appropriate owner’s manual for additional details and instructions.

Courtesy of Mitchell 1.

For more information on Mitchell 1 products and services, automotive professionals can log onto the company’s website at www.mitchell1.com.

You May Also Like

Ignition Coil Output

To see inductance inside the primary windings, use an amp probe placed around the positive wire for the ignition coil.

Kilovolts or kV is the unit used to measure the output of an ignition coil. Some coils can output 20kV to 40 kV. So, how does an ignition coil turn system or battery voltage into these huge voltages? The answer is inductance. 

The ECM provides the voltage to the primary coil winding. The primary winding might have 100 turns around the coil’s core or plates. When the voltage to the coil is turned off, a magnetic field collapses. The collapsing field will generate more than 100 volts thanks to inductance. The energy is transformed by the windings in the secondary with inductance again, but thanks to the 10,000 windings, the voltage is boosted to 40kV at the spark plug’s electrodes. The best way to see inductance inside the primary windings is to use an amp probe placed around the positive wire for the ignition coil. With this setup, you can see the current ramping in the coil and the collapse of the magnetic field. 

HV/EV Battery Pack Replacements

It is difficult to say when a battery pack will need to be replaced.

Compressor Oil for R1234yf

Working on R-1234yf systems is not that different from the R-134a variety.

Fuel Pumps and Cranking

Diagnosing the problem comes down to understanding what causes a loss of fuel pressure.

HV/EV Battery Pack Replacements

It is difficult to say when a battery pack will need to be replaced.

Other Posts

Air Compressors for Shocks (VIDEO)

There are four items you need to pay attention to when installing a new compressor for an air ride system. Sponsored by Wabco.

Mitchell Report Highlights Increase in EV Collision Claims

The report shows both the U.S. and Canada saw a rise in repairable claims frequency in the first quarter of 2023.

Engineering Better Belt Systems

You might not be able to see it, but an accessory drive belt is always both speeding up and slowing down.

Starters & Alternators – Tips For Diagnostics

Here are 4 tips to follow when replacing starters and alternators.