DTC C0055 or P0609. GMC Truck Savana 2003

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2003 🢒 Savana 🢒 Engine 🢒 Engine Controls - 4.8L, 5.3L, and 6.0L 🢒 DTC C0055 or P0609

Circuit Description

The powertrain control module (PCM) converts the signal from the vehicle speed sensor (VSS) to a 128k pulses/mile signal. The electronic brake control module (EBCM) uses the vehicle speed signal from the PCM to calculate the rear wheel speed.

Conditions for Running the DTC

C0055

•	The ignition is ON.

•	The vehicle speed is greater than 13 km/h (8 mph).

P0609

•	The ignition is ON.

•	The vehicle is not moving.

Conditions for Setting the DTC

C0055

Any of the following occurrences may cause the DTC to set.

•	The EBCM detects an open or shorted vehicle speed signal circuit for 500 milliseconds.

•	The EBCM detects the absence of the vehicle speed signal for 5 seconds. If more than one absent wheel speed sensor signal is detected, the condition must be present for 120 seconds to set DTCs.

•	The EBCM detects an erratic vehicle speed signal for 200 milliseconds.

P0609

The PCM detects low voltage on the vehicle speed signal circuit for 45 seconds.

Action Taken When the DTC Sets

•	The EBCM disables the ABS/DRP.

•	The ABS indicator turns ON.

•	The brake warning indicator turns ON.

•	An ECE 13 response may occur. Refer to ABS Description and Operation for a complete description of ECE 13.

Conditions for Clearing the DTC

The Conditions for Setting the DTC are no longer present and you use the scan tool Clear DTCs function.

Diagnostic Aids

Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to Testing for Intermittent Conditions and Poor Connections , Connector Repairs , Testing for Electrical Intermittents and to Wiring Repairs in Wiring Systems.

Test Description

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

This step tests for a voltage signal from the PCM.

This step tests for a missing or erratic vehicle speed signal from the PCM. An assistant may be required to perform this test.

Step	Action	Values	Yes	No
Schematic Reference: Antilock Brake System Schematics Connector End View Reference: Antilock Brake System Connector End Views
1	Did you perform the ABS Diagnostic System Check?	--	Go to Step 2	Go to Diagnostic System Check - ABS
2	Use a scan tool in order to clear the DTCs. Operate the vehicle at a speed greater than the specified value. Does the DTC set?	13 km/h (8 mph)	Go to Step 3	Go to Diagnostic Aids
3	Turn OFF the ignition. Disconnect from the EBCM, the harness connector containing the vehicle speed signal circuit. Turn ON the ignition. Use a DMM in order to measure the DC voltage between the vehicle speed signal circuit and a good ground. Does the voltage measure greater than the specified value?	10 V	Go to Step 4	Go to Step 7
4	Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information. Place the transmission in neutral (N). Set up the DMM in order to measure the DC voltage between the vehicle speed signal circuit and a good ground. Slowly spin the rear wheels by hand for at least 30 seconds and while ensuring the driveshaft is rotating, observe the DMM. Does the voltage measure within the specified range for the entire time that the driveshaft is rotating?	5-7 V	Go to Step 5	Go to Step 7
5	Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 10	Go to Step 6
6	Important: Following EBCM replacement, use the scan tool to perform the Tire Size Calibration procedure. Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Did you complete the replacement?	--	Go to Step 10	--
7	Test the vehicle speed signal circuit for an open, a short to ground or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems Did you find and correct the condition?	--	Go to Step 10	Go to Step 8
8	Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 10	Go to Step 9
9	Important: Perform the setup procedure for the PCM. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls-4.3L or Powertrain Control Module Replacement in Engine Controls - 4.8L, 5.3L, and 6.0. Did you complete the replacement?	--	Go to Step 10	--
10	Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset?	--	Go to Step 3	System OK