Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Test 7A: Left Rear Sensor Signal Failure
1999 Chrysler LHSSECTION Test 7A: Left Rear Sensor Signal Failure
- Diagnostic trouble code may be caused by damaged teeth on tone wheel, missing tone wheel, improperly mounted Left Rear (LR) Wheel Speed Sensor (WSS), sensor air gap too large or too small, operating vehicle on hoist or chassis dynamometer, defective CAB, defective LR WSS, defective outlet valve, or long stops on ice. Go to next step.
- Using scan tool, read diagnostic trouble codes. If scan tool displays LEFT REAR SENSOR CIRCUIT FAILURE, perform TEST 6A . If scan tool does not display LEFT REAR SENSOR CIRCUIT FAILURE, go to next step.
- While monitoring LR WSS, have an assistant drive vehicle while slowly accelerating straight ahead from a stop to 15 MPH. If LR WSS shows zero MPH or lags behind any other WSS more than 3 MPH, go to step 5) . If LR WSS does not show zero MPH or lag behind any other WSS more than 3 MPH, go to next step.
- At this time, LR WSS signal is okay. Diagnostic trouble code may have been set by attempting to stop on very slick road surfaces, or brakes locking due to contamination or overheating. Inspect and repair brakes as necessary. Test is complete.
- Inspect LR WSS for looseness or damage. Repair LR WSS as necessary. If LR WSS is okay, go to next step.
- Inspect LR tone wheel for damaged or missing teeth. Ensure teeth are square and are not bent or nicked. If tone wheel is okay, go to next step. If tone wheel is damaged, replace tone wheel.
- Using feeler gauge, measure air gap between end of LR WSS and teeth on tone wheel at 4 different places on tone wheel. Air gap should be .015-.052" (.38-1.31 mm). If air gap is within specification, go to next step. If air gap is not within specification, repair components as necessary.
- Inspect LR wheel bearings for excessive runout or clearance. If no excessive LR wheel bearing runout or clearance exists, go to next step. If excessive LR wheel bearing runout or clearance exists, repair as necessary.
- Turn ignition off. Disconnect CAB connector. Inspect CAB connector and terminals for damage. Repair connector and terminals as necessary. If connector and terminals are okay, go to next step.
- Using an ohmmeter, check resistance between CAB connector terminals No. 10 (Light Green wire) and No. 2 (Light Green/Dark Blue wire). If resistance is less than 200 ohms, repair Light Green wire for short to Light Green/Dark Blue wire. If resistance is 200 ohms or more, replace LR WSS.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.