For 1990-2009 cars

# SERVICE MANUAL UPDATE-SEC. 6E ENHANCED DTC 36 DIAG. CHART

#### SUBJECT: SERVICE MANUAL UPDATE - SECTION 6E - ENHANCED DTC 36 DIAGNOSTIC CHART AND FACING PAGE

VEHICLES AFFECTED: 1993 "F" MODEL (VIN S - RPO L32)

This bulletin serves to revise the facing page and chart for Diagnostic Trouble Code (DTC) 36 in Section 6E3 "Driveability and Emissions" in the 1993 "F" carline service manual with 3.4L (VIN S) engine.

These replacement pages clarify 24X crankshaft position sensor features and diagnosis.

DTC 36 24X SIGNAL CIRCUIT ERROR 3.4L (VIN S) "F"' CARLINE (SFI)

#### Circuit Description:

The 24X sensor is used to improve spark at engine speed up to approximately 2000 RP-M. DTC 36 will set if.

0 Engine running. 0 The ECM detects that six or more 24X crankshaft position sensor reference pulses have not occurred. 0 DTC 36 diagnostic is executed once per ignition cycle.

Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.

1. The 24X signal RPM should be the same as engine speed up to approximately 2000 RPM at which time it stops. This test determines if the ECM is putting out a 24X signal. 2. This test determines if signal voltage is present up to the ECM. 3. This test determines if system voltage is present at the sensor input. 4. By applying system voltage to the 24X crankshaft position sensor pigtail circuit, pigtail and sensor integrity can be determined. 5. This test determines ground path continuity.

#### Diagnostic Aids:

An intermittent 24X signal error can be caused by poor connections. Ignition feed, reference low and the signal circuits should all be checked for poor connections.

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.