Power Assist Step Malfunction
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. Diagnostic Fault Information
| Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performanc | e | |
|---|---|---|---|---|---|---|
| B+ terminal 1 X1 | 1 | 1 | — | — | ||
| Running Boards Motor Hall Sensor Left Reference terminal 7 X3 | B1B0B 11 | 1 | 1 | — | ||
| Running Boards Motor Hall Sensor Right Reference terminal 1 X3 | B1B0A 11 | 1 | 1 | — | ||
| Left Position Sensor Signal terminal 8 X3 | C1134 11 | 1 | 1 | — | ||
| Right Position Sensor Signal terminal 2 X3 | C1133 11 | 1 | 1 | — | ||
| Left Motor Extend Control terminal 5 X1 | C1182 11 C1183 11 | C1182 13 C1183 13 | C1182 12 C1183 12 | — | ||
| Left Motor Retract Control terminal 2 X1 | C1182 11 C1183 11 | C1182 13 C1183 13 | C1182 12 C1183 12 | — | ||
| Right Motor Extend Control termial 3 X1 | C1180 11 C1181 11 | C1180 13 C1181 13 | C1180 12 C1181 12 | — | ||
| Right Motor Retract Control terminal 6 X1 | C1180 11 C1181 11 | C1180 13 C1181 13 | C1180 12 C1181 12 | — | ||
| Left Position Sensor Low Reference terminal 9 X3 | — | 1 | — | — | ||
| Right Position Sensor Low Reference terminal 3 X3 | — | 1 | — | — | ||
| Ground terminal 4 X1 | — | 1 | — | — | ||
| 1. Assist Steps Inoperative |
Circuit/System Description The running board control module controls the running board actuators to extend or retract the running boards. Each actuator consists of an electric motor and a hall-effect switch. The module supplies a low reference and battery voltage reference source to the hall-effect switch. The running board control module monitors the signal from the hall effect switch on the signal circuit. When the actuator shaft rotates, the hall-effect switch provides pulses to the assist step control module which uses the pulses as counts to determine the location of the assist steps. The running board control module supplies the actuator motor with a PWM 12 V control circuit and a ground control circuit. The running board control module controls the direction of the actuator by changing the polarity of the control circuits. Diagnostic Aids The running boards can be manually deployed by using the assist step switch in the infotainment system while the transmission is in park or neutral. The assist steps will be retracted with a second toggle of the disable switch, if the transmission is switched out of park or neutral, or if vehicle speed exceeds 3 kph (2 mph). If a door is ajar, the boards may retract and extend as vehicle speed goes above and below 3 kph (2 mph). Verify proper operation of door ajar switches and that all doors are tightly shut. If boards are stuck in extended or retracted position, verify there is nothing that can prohibit normal operation such as physical damage, or a build up of mud, snow, or ice on boards and mechanical linkages. Reference Information Schematic Reference Step/Running Board Schematics Connector End View Reference Master Electrical Component List Description and Operation Running Board Description 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.
- Verify scan tool can communicate with K4 Running Board Control Module. ⇒ If scan tool does not communication with module Refer to Scan Tool Does Not Communicate with Device on CAN 1. ⇓ If scan tool communicates with module
- Verify the vehicle is not in Transport Mode ⇒ If the vehicle is in Transport Mode Disable Transport Mode. Refer to: Running Board Description ⇓ If the vehicle is not in Transport Mode
- Verify using the infotainment system menu that the automatic running boards are enabled. ⇒ If the running boards are disabled Enable the running boards by navigating to the switch integrated into the infotainment system. ⇓ If the running boards are enabled
- Verify that the scan tool Right Assist Step Learn Status and Left Assist Step Learn Status parameters are Learned ⇒ If the parameter is Not Learned Refer to: Assist Step Learn ⇓ If the parameter is Learned
- Verify all scan tool Door Ajar Switch parameters change between Active and Inactive when opening and closing the appropriate doors. ⇒ If one or more parameters do not change Refer to Door Ajar Indicator Malfunction. ⇓ If all parameters change
- Verify Right Assist Step Position and Left Assist Step Position parameters change between Retracted Position and Extend to Passenger Position while commanding the running boards to Extend and Retract using the scan tool. ⇒ If one or both parameters do not change, or return to the original position without a command Check for mechanical binding of running board. Refer to Assist Step Replacement for how to manually move boards. ⇓ If parameters change
- Verify the assist steps extend when each vehicle door is opened and retract when the door is closed. ⇒ If the assist steps do not properly extend and retract Refer to Diagnostic Aids. ⇓ If the assist steps properly extend and retract
- All OK.