GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 Prizm 🢒 DTC 🢒 DTC 42 Low System Voltage

Object Number: 365103 Size: SF

Circuit Description

This DTC is used to monitor the voltage level available to the cruise control module. If the voltage level drops below 10 Volts at terminal 9 (BLK/YEL wire), DTC 42 will set.

Diagnostic Aids

Check for the following:

    • Open or high resistance in the BLK/YEL wire.
    • Open, high resistance or low voltage in the power distribution to the ECU-IG fuse in junction block 2.
    • Open or high resistance in the WHT/BLK wire.
    • Open or high resistance in the ground distribution to splice pack 250/G203
    • Vehicle charging system for poor performance.
    • Faulty cruise control module.

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Inspect the following harness connectors for backed out terminals, improper mating, broken lock, improperly formed or damaged terminals or for poor terminal-to-wire connection before replacing the suspect component:

    • Cruise control module connector
    • Junction block 2 C4
    • Splice pack 250
    • Ignition switch

Test Description

The number/description refers to the step in the diagnostic table.

  1. This step tests the condition of the vehicles charging system.

    2.

  2. This step tests the condition of the power feed circuit to the module.

    3.

  3. This step tests for a faulty cruise control module.

Step

Action

Value(s)

Yes

No

1

Was the Cruise Control Diagnostic System Check performed?

--

Go to Step 2

Go to Cruise Control System Check

2

  1. Start the engine.
  2. Turn the headlamps on to high beams.
  3. Set the blower fan speed to high.
  4. Measure the voltage between the positive and negative battery terminals.

Is the voltage within the specified range?

10-14 V

Go to Step 3

Go to Step 6

3

  1. Turn the ignition switch to the lock position.
  2. Disconnect the cruise control module connector.
  3. Re-start the engine.
  4. Measure the voltage between cavity 9 and chassis ground

Is the voltage within the specified range?

10-14 V

Go to Step 4

Go to Step 7

4

  1. Turn the headlamps off.
  2. Turn the blower off.
  3. Turn the ignition switch to the lock position.
  4. Reconnect the cruise control module.
  5. Test drive the vehicle and engage the cruise control to verify the operation.
  6. Stop the vehicle.
  7. Test for DTCs

Did this DTC set?

--

Go to Step 5

Go to Step 8

5

Inspect wires and connectors for proper connections. Refer to diagnostic aids for additional information. If no circuitry problem is found, replace the module.

Is the repair complete?

--

Go to Cruise Control System Check

--

6

Refer to Battery Is Undercharged or Overcharged in Engine Electrical in order to diagnose a low charging condition.

Is the action complete?

--

Go to Cruise Control System Check

--

7

Repair the high resistance in the BLK/YEL wire between the module and junction block 2.

Is the repair complete?

--

Go to Cruise Control System Check

--

8

Malfunction is not present at this time. Refer to diagnostic aids for additional information.

Is the action complete?

--

Go to Cruise Control System Check

--