DTC B3604 or B3605. GMC Truck Sierra Denali 2009

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2009 🢒 Sierra Denali 🢒 Body Systems 🢒 Adjustable Pedals 🢒 DTC B3604 or B3605

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B3604 01: Adjustable Foot Pedal Forward Switch Circuit Short to Battery

DTC B3605 01: Adjustable Foot Pedal Rearward Switch Circuit Short to Battery

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Switch Reference Voltage	1	1	--	--
Forward Switch Signal	2	2	B3604 01	--
Rearward Switch Signal	3	3	B3605 01	--
1. Adjustable Pedals Inoperative 2. Adjustable Pedals Forward Inoperative 3. Adjustable Pedals Rearward Inoperative

The adjustable pedals forward and rearward switches are inputs to the memory seat module (MSM). The MSM supplies the switch assembly with a battery positive reference voltage. When the switch is operated to the forward or rearward direction, battery positive voltage is applied to the forward or rearward switch signal inputs.

Conditions for Running the DTC

System voltage is 9-16 volts.

Conditions for Setting the DTC

The forward and rearward switch signal circuits are active at the same time.

Action Taken When the DTC Sets

The adjustable pedals will be disabled.

Conditions for Clearing the DTC

•	The DTC becomes history when the conditions for setting the DTC are no longer present.

•	The history DTC clears after 100 malfunction-free ignition cycles.

Reference Information

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, observe the scan tool Pedal Forward Switch and Pedal Aft Switch parameters while cycling the adjustable pedal switch between the FWD and RWD position. The appropriate parameter should change between Active and Inactive as commanded.

Circuit/System Testing

Disconnect the harness connector at the adjustable pedal switch.
Ignition ON, test for 11.8-12.2 volts between the appropriate 12-volt reference circuit listed below and ground:

•	X88/Z88 - terminal 11

•	Z75 - terminal 5

⇒	If greater than the specified range, test the 12-volt reference circuit for a short to voltage. If the circuit tests normal, replace the MSM.

⇒	If less than the specified range, test the 12-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.

Verify the scan tool Pedal Forward Switch parameter is Inactive.

⇒	If not the specified value, test the appropriate signal circuit terminal listed below for a short to voltage. If the circuit tests normal, replace the MSM.

•	X88/Z88 - terminal 12

•	Z75 - terminal 6

Verify the scan tool Pedal Aft Switch parameter is Inactive.

⇒	If not the specified value, test the appropriate signal circuit terminal listed below for a short to voltage. If the circuit tests normal, replace the MSM.

•	X88/Z88 - terminal 10

•	Z75 - terminal 4

Install a 3A fused jumper wire between the appropriate signal circuit terminal listed below and B+. The scan tool Pedal Forward Switch parameter should be Active.

•	X88/Z88 - terminal 12

•	Z75 - terminal 6

⇒	If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.

Install a 3A fused jumper wire between the appropriate signal circuit terminal listed below and B+. The scan tool Pedal Aft Switch parameter should be Active.

•	X88/Z88 - terminal 10

•	Z75 - terminal 4

⇒	If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.

If all circuits test normal, test or replace the adjustable pedal switch.

Component Testing

X88/Z88

Ignition OFF, disconnect the harness connector at the adjustable pedal switch.
Test for infinite resistance between the 12-volt reference terminal 11 and the signal terminals listed below:

•	Terminal 10

•	Terminal 12

⇒	If not the specified value, replace the adjustable pedal switch.

Adjustable pedal switch in the FWD position, test for less than 2 ohms between the 12-volt reference terminal 11 and the signal terminal 12.

⇒	If greater than the specified range, replace the adjustable pedal switch.

Adjustable pedal switch in the RWD position, test for less than 2 ohms between the 12-volt reference terminal 11 and the signal terminal 10.

⇒	If greater than the specified range, replace the adjustable pedal switch.

Z75

Ignition OFF, disconnect the harness connector at the adjustable pedal switch.
Test for infinite resistance between the 12-volt reference terminal 5 and the signal terminals listed below:

•	Terminal 4

•	Terminal 6

⇒	If not the specified value, replace the adjustable pedal switch.

Adjustable pedal switch in the FWD position, test for less than 2 ohms between the 12-volt reference terminal 5 and the signal terminal 6.

⇒	If greater than the specified range, replace the adjustable pedal switch.

Adjustable pedal switch in the RWD position, test for less than 2 ohms between the 12-volt reference terminal 5 and the signal terminal 4.

⇒	If greater than the specified range, replace the adjustable pedal switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Accessory Switch Replacement

•	Control Module References for the MSM replacement, setup, and programming