GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 1998 🢒 Cutlass 🢒 DTC 🢒 DTC B1493 Generator F - Term High

Object Number: 422165 Size: LF
Charging System
Body Control Module Components

Circuit Description

This DTC determines if a fault exists that renders the generator F-terminal continuously high.

Conditions for Setting the DTC

All of the following conditions must be met:

    • The engine is running.
    • The powertrain control module (PCM) is sending the engine RPM is zero class 2 serial data message.
    • The PCM is sending the generator PWM is equal to or greater than 64% duty cycle class 2 serial data message for 30 seconds.

Action Taken When the DTC Sets
    • The body control module (BCM) stores DTC B1493 in memory.
    • The volts indicator will illuminate.

Conditions for Clearing the DTC
    • The BCM goes to sleep. The controller reinitializes with the fault cleared.
    • All BCM history codes will be cleared after 100 ignition cycles (from OFF to RUN) with no current codes active during the 100 ignition cycles.
    • Use the Scan Tool .

Diagnostic Aids
  1. When the diagnostics direct you to take electrical measurements at the terminal assignments of the junction blocks, refer to Power Distribution Schematics in Wiring Systems.
  2. If the DTC is a history DTC, the problem may be intermittent. Perform the tests shown while wiggling the wiring and connectors. This can often cause the malfunction to appear.

Test Description

The numbers listed below refer to the numbers on the diagnostic table.

  1. This step determines if the PCM is reading a false generator PWM input.

    2.

  2. This step determines if the PCM is reading a high generator PWM measurement.

    3.

  3. This step determines if CKT 23 has a short to B+ condition.

Step

Action

Value(s)

Yes

No

1

Was the body control module (BCM) system check performed?

--

Go to Step  2

Go to Body Control Module System Check

2

  1. Turn the ignition switch to the RUN position with the engine OFF.
  2. Disconnect the generator.
  3. Read the generator PWM, using the Scan Tool .

Is the generator PWM equal to the specified value?

0%

Go to Step  3

Go to Step  5

3

  1. Reconnect the generator.
  2. Start the engine.
  3. Use the Scan Tool in order to read the PCM.

Is the generator PWM reading greater than the specified value?

50%

Go to Step  4

Go to Step  5

4

Replace the generator. Refer to Generator Replacement in Engine Electrical.

Is the circuit repair complete?

--

Go to Step  8

--

5

  1. Disconnect the generator connector.
  2. Disconnect the PCM connector C2.
  3. Use the J 39200 DMM in order to measure the voltage in CKT 23 at the generator terminal C.

Is the measured voltage equal to the specified value?

0 V

Go to Step  7

Go to Step  6

6

Repair the short to B+ in CKT 23 between the generator terminal C and the PCM connector C2 terminal 29 (connector C1 terminal 53 for LD9). Refer to Wiring Repairs in Wiring Systems.

Is the circuit repair complete?

--

Go to Step  8

--

7

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls.

Is the repair complete?

--

Go to Step  8

--

8

Clear the DTCs from the memory.

Are the DTCs cleared from the memory?

--

Go to Body Control Module System Check

--