By Core Brake Parts Tech Team — Circleville, OH warehouse
An ABS light that stays on in a 2003-2008 Infiniti G35 means the ABS control unit has found a fault and switched anti-lock braking off. Your normal brakes still work, but the wheels can lock in a panic stop, and on cars with VDC the SLIP and VDC OFF lights usually come on too. The most common cause is a wheel speed sensor circuit, followed by a dirty or damaged tone ring, wiring and connector faults, and less often the ABS actuator and control unit itself.
How the G35 ABS and VDC System Works
Every G35 has a wheel speed sensor at each corner. The sensor reads a toothed ring or magnetic encoder that turns with the hub, and sends a pulse signal to the ABS actuator and electric unit, the combined hydraulic pump, valve block and control module. When one wheel slows much faster than the others under braking, the unit pulses brake pressure to that wheel so it keeps turning and you keep steering control.
On cars equipped with Vehicle Dynamic Control (VDC), the same control unit also runs traction and stability control, using the wheel speed signals plus a yaw rate sensor. That is why one bad wheel sensor on a G35 often lights up ABS, SLIP and VDC OFF all at once. The system shuts those functions down together as a fail-safe; it does not mean three separate parts failed.
Wheel speed sensors come in two types. A passive sensor makes its own AC signal from a magnet and coil, and its signal is weak at very low speed. An active sensor needs a supply voltage from the control unit and sends a clean digital signal. Infiniti's 2012 wheel speed sensor bulletin for 2007-2013 Infiniti models (which covers the 2007-2008 G35 sedan) tests the sensor with an active wheel sensor tester and checks for battery voltage at the sensor connector, so later G35s use active sensors. Confirm the sensor type for an earlier car in the factory service manual before testing it with an ohmmeter.
Symptoms and What Each Light Combination Tells You
| What you see | What it usually points to |
|---|---|
| ABS, SLIP and VDC OFF on together, brakes feel normal | A wheel speed sensor, its wiring or tone ring; the control unit has disabled ABS and VDC as a group |
| Lights come on only once the car is moving, go off after a restart | Intermittent sensor signal: debris on the sensor tip, a contaminated encoder, or a loose connector |
| Lights came on right after a brake job or hub replacement | Sensor not fully seated, harness pulled or pinched, or connector left unplugged |
| SLIP and VDC OFF on, ABS light off | A VDC-side input such as the yaw rate or steering angle sensor rather than a wheel sensor |
| Red BRAKE light together with ABS | Low fluid or a condition that also affects brake force distribution; inspect the brakes before driving |
| Many warning lights at once, with rough running or no start | Often an engine-side or charging fault, not a brake part (see the recall notes below) |
If the red brake warning light is on with the parking brake released, check the fluid level in the master cylinder reservoir first. A low level usually means worn pads or a leak. Do not drive the car hard until you know which.
Common Causes, Most Likely First
1. Wheel speed sensor or its circuit
The sensor lives in the hub area where it takes heat, water, salt and brake dust. Infiniti's bulletin lists the codes that point here: C1101 through C1104 are the Wheel Speed Sensor 1 codes and C1105 through C1108 are the Wheel Speed Sensor 2 codes, one code per wheel in each group. A scan tool that reads ABS codes tells you which corner to look at, so you are not guessing.
2. Contaminated or damaged tone ring (magnetic encoder)
The bulletin states that contamination on the tone ring can cause intermittent errors, and has technicians inspect the tone wheel and bearing for damage, missing teeth, cracks, corrosion or looseness. Metallic filings stuck to the sensor tip or encoder distort the signal, and a worn wheel bearing lets the ring wobble. If the encoder or bearing is bad, the fix is the tone wheel or hub bearing, not a new sensor.
3. Tire size or pressure mismatch
For Wheel Speed Sensor 2 codes, the bulletin has technicians check tire pressure and tire wear early in the procedure. The control unit compares wheel speeds, so one low tire or a mismatched tire size on one corner can look like a sensor fault.
4. Wiring and connectors
The sensor harness runs past the suspension and flexes every time the wheel moves. Chafed insulation, a pinched lead after a brake or suspension job, or a corroded connector will set the same codes as a failed sensor. The bulletin has the technician inspect both connector cases for bent pins, deformation, corrosion and contamination and check the harness for shorts before replacing parts.
5. ABS actuator and electric unit
This is the expensive one, and it is the last step in the factory diagnosis, not the first. The bulletin only calls for replacing the ABS actuator after the sensor, harness and supply voltage checks point to it, or when the same code returns after a new sensor and a clean tone ring. Low battery voltage can also upset electronic modules, so rule out a weak battery or charging fault first.
How to Diagnose It Step by Step
- Read the ABS codes. A basic engine code reader does not see ABS codes. You need a scan tool that reads the ABS and VDC module. Write down every code before clearing anything.
- Clear and duplicate. Infiniti's bulletin says the code must be active before you diagnose it: clear past codes, then drive above 13 mph and see which code resets. A code that will not come back is not proof a part has failed.
- Look before you replace. Pull the wheel at the corner the code names. Inspect the sensor for damage, the tip for debris, the lead for chafing, and the connector for corrosion.
- Test the signal. Spin the wheel and confirm the sensor produces a signal (the dealer uses an active wheel sensor tester; live wheel speed data on a capable scan tool or a lab scope does the same job). A dead sensor with good supply voltage at the connector is a bad sensor.
- Check tires and the bearing. Confirm pressures and tire sizes match, and check the hub for play or a damaged encoder.
- Verify the repair. Clear codes, run the engine, road test for at least five minutes, then recheck for codes, as the bulletin describes.
The bulletin puts it plainly: do not replace a sensor based on the code alone without confirming a specific issue. That rule saves G35 owners from throwing sensors at a problem that is really a dirty encoder or a broken wire.
Recalls and Other Warning-Light Causes to Rule Out
NHTSA's recall database lists no ABS component recall for the 2003-2008 G35. Two early recalls are worth knowing about when warning lights appear. Campaign 03V200000 covers a brake stop lamp switch on certain 2003 G35 sedans and coupes that could stop the brake lights from working. Campaign 03V455000 covers crank and cam position sensors on certain 2003 cars that could turn on the Service Engine Soon light, cause a no start, or stall the engine. A G35 that shows a dash full of lights along with engine trouble is often an engine-side problem, not an ABS fault. Run your VIN through the NHTSA recall lookup or ask an Infiniti retailer to confirm whether any open campaign applies to your car.
If SLIP and VDC OFF are on but the scan tool shows no wheel speed code, look at the other VDC inputs such as the yaw rate sensor. A scan tool reading is what separates those from a wheel sensor problem.
Fixing It and What to Replace at the Same Time
Most G35 ABS light repairs come down to a single wheel speed sensor, a cleaned or replaced tone ring, a repaired harness, or a hub bearing. Replacing a sensor is usually one fastener and one connector plus clipping the lead back into its brackets, but a sensor seized in the knuckle can break on removal, so soak it with penetrant first. After installation, make sure the sensor is fully seated: a replacement sensor that was not pushed all the way in is one of the most common reasons the same code comes right back.
If the ABS light started after a brake job, the sensor lead is the first thing to check, since the caliper and rotor come off right next to it. While you are in there, check pad thickness and rotor condition. Brembo-equipped G35s take different pads and rotors than the standard brakes, so match the parts to your car. We carry Hawk Ceramic Street front pads for 2003-2007 G35s with Brembo brakes and EBC slotted front rotors for early G35 automatics, plus the full range of brake pads, brake rotors and brake hardware kits.
Difficulty: reading codes and replacing one sensor is a home-garage job with a floor jack, stands and an ABS-capable scan tool. Harness repair takes a wiring diagram and patience. Actuator replacement opens the hydraulic system and may need bleeding and initialization procedures from the factory service manual, so most owners leave that one to a shop.
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Shop Brake Parts →Frequently Asked Questions
Is it safe to drive a G35 with the ABS light on?
The normal brakes still work, but anti-lock and, on VDC cars, stability control are off, so the wheels can lock in a hard stop or on a slick road. Drive gently and get it diagnosed soon. If the red BRAKE light is also on, check the fluid and brakes before driving at all.
Why are the ABS, SLIP and VDC OFF lights all on at the same time?
The ABS and VDC functions share the same wheel speed signals and control unit. When one input fails, the unit shuts off anti-lock, traction and stability functions together as a fail-safe, so all three lights come on from one fault.
Will disconnecting the battery clear the ABS light?
It may turn the light off briefly, but a real fault returns as soon as the control unit sees the bad signal again, usually once you are moving. Read the stored codes first so you do not lose the clue to which wheel is at fault.
Can new brake pads or rotors cause an ABS light?
The pads and rotors themselves do not, but the job can. A pinched or stretched sensor lead, a connector left unplugged, or a sensor knocked out of position will set a wheel sensor code. Check the sensor at the corner you worked on first.
Do I need to replace the whole ABS module?
Rarely as a first step. Infiniti's diagnostic procedure only points to the ABS actuator after the sensor, wiring, connectors, tone ring and supply voltage check out, or when the same code returns after those fixes.
Sources
- Infiniti Service Bulletin ITB10-056a, ABS/VDC Wheel Speed Sensor Diagnosis (NHTSA) - 2007-2013 Infiniti applicability, C1101-C1108 code groups, active DTC rule, 13 mph duplication drive, do not replace a sensor on the code alone
- Nissan Service Bulletin NTB10-102a, ABS/VDC Wheel Speed Sensor Diagnosis (NHTSA) - connector inspection, supply voltage check, tone ring contamination, tire checks, actuator as the last step, repair verification test
- NHTSA recall data, 2003 Infiniti G35 - campaigns 03V200000 (stop lamp switch) and 03V455000 (crank and cam position sensors)
- Brake and Front End: Understanding ABS Passive Wheel Speed Sensors - how passive sensors generate a signal; sensors not pushed fully in as a common fault; debris, corrosion and bearing play
- MOTOR Magazine: Brake Shop, Wheel Speed Sensors - active vs passive sensors, metallic filings, air gap and worn bearings as failure causes
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