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pcm-p1574


scottyg

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my 01 sts just came up with a message on the dash saying service electrical system,and the traction control light is lit on the dash.this is the only current code that came up-pcm-p1574 any ideas? thanks...

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Let's begin with the simple possibility; there are two switches actuated by the brake pedal arm. Be sure the electrical connectors are clean and tight and the harness is not damaged. Also be sure the switches are adjusted to operate properly when the brake pedal arm is moved.

The switches are easily removed from the bracket by rotating the switch body CCW about 45 degrees (or less).

Does your cruise control operate?

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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P1574 Stoplamp Switch Circuit

Since the traction light is on, the switch may be stuck ON. See if the stoplamps are lit after you shut off the car and get out. In any case. JimD is suggesting that you check out the stop lamp switch and telling you how to get started.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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This diagnostic test functions on the assumption that sudden decrease in a non-drive, wheel speed must be caused by a brake application. Non-drive wheel speed and stoplamp switch status are supplied to the PCM through serial data from the Electronic Brake Control Module (EBCM). If there is a 2.5 MPH or greater decrease of non-drive wheel speed in 0.4 seconds and a transition of the TCC or extended travel contacts of the TCC brake switch without a transition of the stop lamp brake switch, DTC P1574 is set.

Conditions for Running the DTC

• DTCs P0502, P0503, P0719, P0724, P1575 and P1602 not set.

• Traction control and antilock brake systems have not failed.

• Traction control and antilock brake systems are not active.

• Non-drive wheel speed goes above 20 MPH and then doesn't go below 4 MPH.

Conditions for Setting the DTC

A 2.5 MPH or greater decrease in non-drive wheel speed in 0.4 second and extended travel brake switch or TCC brake switch indicating brakes applied and no transition noticed in the stoplamp contacts of the stop lamp switch.

Action Taken When the DTC Sets

PCM will set the stoplamp switch status to not applied.

• The Malfunction Indicator Lamp (MIL) will not illuminate.

• No message will be displayed.

Conditions for Clearing the DTC

• A History DTC will clear after forty consecutive warm-up cycles with no failures of any non-emission related diagnostic test.

• A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.

• Use a scan tool to clear DTCs.

• Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended.

Diagnostic Aids

DTC P1574 indicates the stoplamp switch signal to the EBCM or the EBCM's ability to send the stop lamp switch signal to the PCM has failed. Refer to ABS/TCS DTC's for diagnosis of the stoplamp switch signal and the EBCM.

That being said...very good chance the brake switch has moved from it's correct position. Pretty easy to have this happen on these cars.

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Same cause. If the brake switch doesn't work, the ABS logic doesn't have all its inputs.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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ABS p1574..

The stop lamp switch signal informs the electronic brake control module (EBCM) when the brake pedal is pressed.

Conditions for Running the DTC

The vehicle speed is greater than 40 km/h (25 mph).

Conditions for Setting the DTC

The stop lamp switch input was active for 2 consecutive ignition cycles.

Action Taken When the DTC Sets

• The EBCM disables the TCS for the duration of the ignition cycle.

• The Traction Control indicator turns ON.

• The ABS remains functional.

Conditions for Clearing the DTC

• The condition for the DTC is no longer present and the DTC is cleared with a scan tool.

• The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids

Possible causes of this DTC are the following conditions:

• The stop lamp switch circuit is shorted to voltage.

• The stop lamp switch is misadjusted.

• The stop lamp switch is stuck closed.

• A brake pedal that is binding.

• Both brake light bulbs are burned out.

The brake switches in these cars are known to move around.

I, myself, have had codes for 'extented brake switch travel'. Plus lost of cruise control.

Reset the brake switches. All is fine..

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