Inspection Procedure 1: the TPMS Warning Light Stays on
INSPECTION PROCEDURE 1: The TPMS Warning Light Stays On.TPMS Warning Light Signal Circuit Connectors: C-03, C-04, C-121:
CIRCUIT OPERATION
- The TPMS warning light will illuminate when the tire inflation pressure of any road wheel is below 174 kPa (25.3 psi).
- Furthermore, the TPMS warning light illuminates for three seconds immediately after the ignition switch is turned to the "ON" position. This is a bulb check of the TPMS warning light.
TECHNICAL DESCRIPTION (COMMENT)
If the TPMS warning light illuminates for three seconds after the ignition switch is turned to the "ON" position, and does not go out, diagnose the signal circuit of the TPMS warning light as follows (from Step 6).
TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CASE:)
- Low tire inflation pressure
- Punctured tire
- Damaged tire valve grommet and/or valve core
- Inaccurate tire pressure sensor of the TPMS transmitter
- TPMS warning light signal harness wire shorted to ground
- Malfunction of the combination meter
- Malfunction of the TPMS receiver
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A
STEP 1. Inspect the all tires.
Visually check all the tires for any sign of air leak or puncture.
Q:Are all the tires in good condition?
YES: Go to Step 2.
NO: Replace the valve grommet or valve core, or repair the flat tire. Replace the tire if necessary. Then go to Step 2.
STEP 2. After the tire inflation pressure is adjusted and the TPMS transmitter sends inflation pressure information on it, check the TPMS warning light. TPMS Warning Light Check
(1) Wait until the tires cool down, and adjust all the tire inflation pressures to the value specified on the tire pressure label.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
(2) Connect scan tool MB991958 to the data link connector.
(3) Turn the ignition switch to the "ON" position.
(4) Execute "Tire Pressure Sensor Check" on scan tool MB991958 "Special Function". Tire Pressure Sensor Check
(5) Check the TPMS warning light. TPMS Warning Light Check
Q:Is the TPMS warning light turned off?
YES: The procedure is complete.
NO: Go to Step 3.
STEP 3. Check the tire inflation pressure again.
Use a tire pressure gauge to check that all the tire inflation pressures meet the value specified on the tire pressure label.
Q:all the tires in good condition?
YES: Go to Step 4.
NO: Replace the valve grommet or valve core, or repair the damaged tire. Replace the tire if necessary. Then return to Step 2.
STEP 4. Check the TPMS warning light. TPMS Warning Light Check
Turn the ignition switch to the "ON" position. The TPMS warning light should illuminate for three seconds, and then go out momentarily.
NOTE: If the TPMS warning light goes out momentarily, the TPMS warning light signal circuit is correct. However, as DTC C1912, C 1922, C 1932 or C 1942 (TPMS transmitter abnormality -Tire air pressure low) has been set, the TPMS warning light illuminated.
Q:Turn the ignition switch to the "ON" position. Does the TPMS warning light illuminate for three seconds, and then go out momentarily?
YES: Go to Step 5.
NO: Go to Step 6.
STEP 5. Using scan tool MB991958, read the diagnostic trouble code.
Use scan tool MB991958 to check whether DTC C1912, C1922, C1932 or C1942 (TPMS transmitter abnormality -Tire air pressure low) is set. C1912 C1922 C1932 C1942
Q:Is DTC C1912, C1922, C1932 or C1942 set?
YES: Carry out troubleshooting for DTC C1912/C1922/C1932/C1942 (TPMS transmitter abnormality -Tire air pressure low).
NO: Replace the TPMS receiver and execute "Tire Pressure Sensor ID Registration" on scan tool M B991958 "Special Function". Then go to Step 9.
STEP 6. Check TPMS receiver connector C-121 and combination meter connector C-04 for loose, corroded or damaged terminals, or terminals pushed back in the connector. Pinout Values and Diagnostic Parameters
Connector: C-04:
Connector: C-121:
Q:Are TPMS receiver connector C-121 and combination meter connector C-04 in good condition?
YES: Go to Step 7.
NO: Repair or replace the connector. Refer to Harness Connector Inspection.
STEP 7. Check the wiring harness between TPMS receiver connector C-121 (terminal 1 and 2) and combination meter connector C-04 (terminal 3 and 4). Pinout Values and Diagnostic Parameters
Connector: C-04:
Connector: C-121:
Connector: C-03:
NOTE: Also check joint connector (3) C-03 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If joint connector (3) C-03 is damaged, repair or replace the connector.
Q:Are the wiring harness TPMS receiver connector C-121 (terminal 1 and 2) and combination meter connector C-04 (terminal 3 and 4) in good condition?
YES: Repair or replace it. Then go to Step 9.
NO: Go to Step 8.
STEP 8. Check the combination meter.
Check that the combination meter warning lights and indicators other than TPMS warning light illuminate normally.
Q:Are there any faults on the combination meter?
YES: Replace the combination meter assembly. Then go to Step 9.
NO: Replace the TPMS receiver and execute "Tire Pressure Sensor ID Registration" on scan tool MB991958 "Special Function". Then go to Step 9.
STEP 9. Retest the system.
Q:Turn the ignition switch to the "ON" position. Does the TPMS warning light illuminate for three seconds, and then go out?
YES: The procedure is complete.
NO: Repeat the troubleshooting from Step 1.