Normal Operation
WARNING: This page is about a different car, the 2012 Ford Pickup. 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