Failed rear wiper motor assembly (most common, due to internal wear or water intrusion).; Broken or corroded wiring between the body and liftgate (flexing harness).; Defective rear wiper relay or fuse.; Faulty rear wiper switch or stalk.; Poor ground connection at the motor or body.; BCM internal fault (rare).

DTC codes / B01xx · Airbags, seats, doors, lights and comfort systems / B0188

B0188Rear Wiper Motor Circuit

Q: What does code B0188 mean?

Rear Wiper Motor Circuit. B0188 indicates that the body control module (BCM) has detected a fault in the rear wiper motor circuit, which includes the motor, wiring, relay, and switch inputs. The BCM monitors voltage and current on the circuit and sets this code when the signal is outside the expected range during wiper operation or self-test.

B0188 indicates that the body control module (BCM) has detected a fault in the rear wiper motor circuit, which includes the motor, wiring, relay, and switch inputs. The BCM monitors voltage and current on the circuit and sets this code when the signal is outside the expected range during wiper operation or self-test.

SystemBody

Code typeGeneric (all makes)

SeverityLow

Fix difficultyIntermediate

AreaAirbags, seats, doors, lights and comfort systems

Symptoms you may notice

Rear wiper does not operate in any mode (intermittent, low, or high).
Rear wiper runs continuously without input from the switch.
Rear wiper parks in the wrong position or fails to return to rest.
Often no symptoms besides the warning light, especially if the fault is intermittent.
Blown fuse for the rear wiper circuit.
Rear washer pump may also be inoperative if it shares a common ground or power feed.

Common causes, most likely first

Failed rear wiper motor assembly (most common, due to internal wear or water intrusion).
Broken or corroded wiring between the body and liftgate (flexing harness).
Defective rear wiper relay or fuse.
Faulty rear wiper switch or stalk.
Poor ground connection at the motor or body.
BCM internal fault (rare).

How to diagnose and fix it

Check the rear wiper fuse and replace if blown; verify power at the fuse.
Inspect the wiring harness at the liftgate hinge for chafing, breaks, or corrosion; repair as needed.
Test the rear wiper motor directly by applying power and ground; replace if it does not run.
Check the rear wiper relay by swapping with a known-good relay of the same type.
Test the rear wiper switch with a multimeter for continuity in each position; replace if faulty.
Verify ground connections at the motor and body; clean and tighten as necessary.
Clear the code and retest; if it returns, perform a voltage drop test on the circuit to locate high resistance.

Liftgate harness and motor park switch failures

The liftgate harness flexes every time the hatch opens, so a broken wire inside intact insulation is a common hidden cause that a visual inspection may miss.
A rear wiper motor with a faulty internal park switch can set B0188 even though the motor runs, because the BCM expects a specific signal when the wiper reaches its rest position.
Water intrusion into the motor housing often corrodes the internal contacts and causes intermittent operation that sets the code only in damp weather.
The BCM may set B0188 if the rear wiper switch is left in the on position when the vehicle is started, as a self-test sees unexpected voltage.
A weak battery or low charging system voltage can cause the BCM to misreport circuit faults, so always verify battery condition before replacing parts.

Can I keep driving with B0188?

The vehicle is safe to drive because the rear wiper is not a critical safety system, but avoid operating the rear wiper until repaired to prevent further damage. In rainy conditions, use extra caution as rear visibility may be reduced.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.