C1150
Two Speed Rear Axle Input Switch Circuit Short to Vbatt
Chassis Transmission Control Rear Axle Switching 🔴 Serious — Stop or limit driving
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What This Actually Means
In plain language — no jargon

The rear axle speed sensor is sending a constant high voltage signal to the ECU instead of switching between low and high like it should. It's like a light switch stuck in the 'on' position rather than flicking on and off.

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Symptoms You May Notice
3 known symptoms for this code
Check Engine Light illuminated
Traction control or stability control malfunction
Erratic shifting in automatic transmission
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors the Two Speed Rear Axle Input Switch for voltage transitions that indicate gear engagement changes. The circuit should toggle between ground (low ~0V) and battery voltage (high ~12V). A short to Vbatt means the signal is stuck high, preventing the ECU from detecting axle speed transitions.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Switch Voltage 0V to 12V transitions Continuously 12V (short to Vbatt)
Signal Frequency Variable frequency based on axle speed No frequency variation detected
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Wiring harness connector
Inspect connector at rear axle for corrosion or moisture; clean contacts with electrical cleaner.
2
Wiring and insulation
Check wiring from axle to ECU for cracks, pinches, or exposed conductor contacting battery voltage sources.
3
Two Speed Rear Axle Input Switch
Replace the switch if wiring is intact but voltage remains shorted to battery.