Normal Operation
WARNING: This page is about a different car, the 2014 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
When the MSS is engaged to lock the rear differential, a PWM signal is sent to the ELD field coil by the TCCM through the differential lock control circuit. This PWM signal is initially 98% duty cycle to lock the differential and decreases to 40% duty cycle once the differential is locked. If the differential lock control circuit is open or shorted to ground, the TCCM senses a signal is not reaching the differential and sets a DTC.
- DTC P187C:00 (Differential Lock-Up Control Circuit/Open: No Sub Type Information) - The TCCM sends a signal to the differential to lock the differential. The TCCM C2371B pin 9 senses that the differential lock control circuit is open. The ELD differential is not engaged.
- DTC P187D:00 (Differential Lock-Up Control Circuit Low: No Sub Type Information) - The TCCM sends a signal to lock the differential. The TCCM C2371B pin 9 senses that the differential lock control circuit is shorted to ground. The ELD differential is not engaged.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- TCCM