GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 1998 🢒 Achieva 🢒 DTC 🢒 DTC C1294 Brake Lamp Switch Circuit Always Active

Object Number: 161025 Size: SF
ABS Components
ABS/ETS Schematics

Circuit Description

DTC C1294 determines the proper operation of the brake switch. Proper operation of the brake switch is important because the brake switch activates the ABS and inhibits the ETS when the brake switch is on. The brake switch deactivates the ABS when the brake switch is off. The following conditions always occur when the brake switch is on:

    • ABS operation is requested.
    • ETS operation is inhibited.

Conditions for Setting the DTC

DTC C1294 can set if the vehicle's speed is greater than 40 km/h (25 mph).

A malfunction exists if the brake was always on during two consecutive drive cycles.

Action Taken When the DTC Sets
    • A malfunction DTC stores.
    • ABS operation remains.
    • ETS operation is inhibited.

Conditions for Clearing the DTC
    • The condition responsible for setting the DTC no longer exists and the Scan Tool Clear DTCs function is used.
    • 100 drive cycles pass with no DTC(s) detected. A drive cycle consists of starting the vehicle, driving the vehicle over 16 km/h (10 mph), stopping and then turning the ignition off.

Diagnostic Aids

Use the enhanced diagnostic function of the Scan Tool in order to measure the frequency of the malfunction.

Step

Action

Value(s)

Yes

No

Important: Zero the J 39200 test leads before making any resistance measurements. Refer to the J 39200 user's manual.

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check

2
  1. Turn the ignition switch to the OFF position.
  2. Verify that there is no pressure on the brake pedal.
  3. Observe the rear brake lamps.

Are the rear brake lamps on?

--

Go to Step 3

Go to Step 5

3

Disconnect the stoplamp switch connector.

Are the rear brake lamps on?

--

Go to Step 8

Go to Step 4

4

Inspect the adjustment of the stoplamp switch.

Is the stoplamp switch adjusted correctly?

--

Go to Step 10

Go to Step 9

5
  1. Disconnect the EBCM connector.
  2. Turn the ignition switch to the RUN position.

    3. Do not start the engine.

  3. Use the J 39200 in order to measure the voltage between the EBCM connector terminal 16 and ground.

Is the voltage within the specified range?

0-1 V

Go to Step 6

Go to Step 8

6
  1. Turn the ignition switch to the OFF position.
  2. Inspect the EBCM connector and the EBCM harness connector for the following conditions:
    3. • Terminal damage
    • Poor terminal contact
    • Terminal corrosion

Is there evidence of poor terminal contact, terminal corrosion, or damaged terminals?

--

Go to Step 11

Go to Step 7

7
  1. Reconnect the EBCM connector.
  2. Install a Scan Tool .
  3. Turn the ignition switch to the RUN position.

    4. Do not start the engine.

  4. Start the engine.
  5. Test drive the vehicle obtaining a speed at least 40 km/h (25 mph).
  6. Repeat the drive cycle, and steps 3,4, and 5 at least two additional times.
  7. Use the Scan Tool in order to inspect for DTCs.

Does DTC C1294 set as a current DTC during the last three drive cycles?

--

Go to Step 12

Go to Step 13

8

Repair the short to voltage in CKT 17 or 20.

Is the repair complete?

--

Go to Diagnostic System Check

--

9

Adjust the stoplamp switch.

Is the repair complete?

--

Go to Diagnostic System Check

--

10

Replace the stoplamp switch.

Is the repair complete?

--

Go to Diagnostic System Check

--

11

Replace all of the terminals and connectors that exhibit the following conditions:

    • Poor terminal contact
    • Corrosion
    • Damaged terminal(s)

--

Go to Diagnostic System Check

--

12

Replace the EBCM.

Is the repair complete?

--

Go to Diagnostic System Check

--

13

The malfunction is intermittent or is not present at this time. Refer to Diagnostic Aids for more information.

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