HIGH IDLE/INTERMITTENT CODE 26 INCORRECT TPS SENSOR

VEHICLES AFFECTED: All 1981-1985 Models Equipped With DFI

Some 1981-1985 DFI equipped vehicles may experience a high idle and/or an intermittent code 26, under various operating conditions due to the installation of an improper Throttle Position Sensor (TPS) while servicing the vehicle.

The 1981 V8-6-4 TPS, although similar in appearance, is different electrically than the ones used for 1982-1984 HT4100 equipped vehicles. The ECM will not interpret the throttle angle correctly if these parts are interchanged. A 1981 V8-6-4 TPS installed on an HT4100 equipped vehicle can be diagnosed by a higher than normal throttle angle at warm idle (i.e. 4-6 degrees on parameter .0.1 vs. approximately 0-2 degrees on a normal vehicle) when the TPS is properly adjusted. The 1984 TPS is different in appearance than the 1981-1983 TPS.

As will all electrical and emissions-related parts, it is essential that the correct service part be used. Part numbers are as follows:

Service TPS Model Year Engine P/N 'I.D.' Application ---------- ------ --- ------ ------------ Type 1 1981-1984 368 CID 17067979 59085 'D' Limousine & (V8-6-4) 1981 C,E,K Type 2 1982-1983 HT4100 17078259 70898 C, E, K Type3 1984-1985 HT4100 17110352 74958 DW/DM/E/K (Excl. Limousine)

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.