What Does C1748 Mean?
The switch input circuit in the chassis control module has a short to ground. This typically affects a mode select switch, ride control switch, or stability control input that communicates driver preferences to the suspension or chassis module. The driver may notice the system defaulting to a standard or fail-safe mode, with a dash warning light illuminated.
Common Causes
35%
Damaged or chafed wiring harness shorting switch signal wire to ground
30%
Faulty mode select switch with internal short circuit
20%
Corroded or water-damaged connector pins at switch or module
10%
Chassis control module internal circuit failure
5%
Ground contamination on switch circuit from adjacent wiring
Diagnostic Steps
1
Access freeze frame data to determine conditions when the fault was set, noting vehicle speed and operating mode at the time of failure.
2
Locate the switch input connector at the chassis module and measure resistance to ground on the signal wire — should read infinite (OL) with the switch disconnected; any measurable resistance indicates a short to ground in the harness.
3
Disconnect the mode select switch and check continuity between the switch signal pin and ground — if continuity exists with the switch disconnected, the wiring harness has a short.
4
Inspect the wiring harness routing from the switch to the module for pinch points, abrasion against metal edges, or moisture intrusion at connectors.
5
If the harness checks good, test the switch itself by measuring resistance across its terminals in each position — compare to manufacturer specifications (typically open/closed states with specific resistance values).
Estimated Repair Cost
$75 - $450
Parts + labor, varies by vehicle and location
The switch input circuit in the chassis control module has a short to ground. This typically affects a mode select switch, ride control switch, or stability control input that communicates driver preferences to the suspension or chassis module. The driver may notice the system defaulting to a standa...
The most common cause of C1748 (Switch input Circuit Short to Gnd) is: Damaged or chafed wiring harness shorting switch signal wire to ground
Typical repair costs for C1748 range from $75 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Generally safe to continue driving. The system will operate in a default or fail-safe mode. Ride quality or handling preferences may not be adjustable. No immediate safety risk, but have it diagnosed at your convenience.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C1748 to identify the root cause.
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Quick Info
Category
Chassis
System
Chassis Electronics / Suspension Control
Difficulty
Type
Manufacturer
Recommended Tools
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