Engine Controls - Powertrain Grounds

Model All Model

Group Fuel System(14)

Number KT2009083101

Date Monday, August 31, 2009

Area N.America

Subject
Powertrain Grounds

- Description

Powertrain Grounds

Upon encountering powertrain DTC's, check that the powertrain main ground is good before attempting any repairs.

When diagnosing any "P" or "C" Diagnostic Trouble Code (DTC) in which normal diagnostic steps do not quickly reveal the problem, check that the powertrain assembly is properly grounded to the body/chassis/battery.

Powertrain assemblies all have at least one ground to body/chassis/battery and in some cases more. A poorly grounded powertrain assembly does not necessarily produce a "string" of DTC's; check the connections even if you only retrieve one or two DTC's. Not identifying the poor ground can (and does) lead to many hours being spent and parts being replaced unneccessarily.

Be aware that a quick voltage drop check between the powertrain and body/chassis/battery while at engine idle or in the shop under low load conditions may not reveal this concern. Powertrain ground requirements increase linearly (and substantially) with higher RPM/load conditions. It may be necessary to drive the vehicle under similar RPM/load conditions as when the code set while taking voltage drop recordings with a "min/max" capable digital volt meter.

Any indications of poorly grounded powertrain assembly should be investigated and corrected prior to performing any further in-depth repairs.