DTC 71

DTC 71: Lateral G-Sensor System









CIRCUIT OPERATION
The lateral G-sensor detects the acceleration level in the left/right direction of the vehicle, converts the signals into voltage signals and then sends that signal to the ABS-ECU.

ABS DTC SET CONDITIONS
This code is output in the following cases:
^ When the G-sensor output is 0.5 V or lower or 4.5 V or higher (disconnected lateral G-sensor or lateral G-sensor short circuit)
^ If the lateral G-sensor output power does not change (lateral G-sensor output fastening).

TROUBLESHOOTING HINTS
The most likely causes for DTC to set are:
^ Malfunction of the lateral G-sensor
^ Damaged wiring harness and connector
^ Malfunction of the brake modulator hydraulic unit (integrated with ABS-ECU)

DIAGNOSIS
Required Special Tools:
^ MB991223: Harness Set
^ MB991529: Diagnostic Trouble Code Check Harness
^ MB991958: Scan Tool (MUT-III Sub Assembly)
^ MB991824: Vehicle Communication Interface (V.C.I.)
^ MB991827: MUT-III USB Cable
^ MB991911: MUT-III Main Harness B

STEP 1. Using scan tool MB991958, check data list.

CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the LOOK (OFF) position before connecting or disconnecting scan MB991958.





1. Connect scan tool MB991958 as shown in the illustration.
2. Start the engine.
3. Set scan tool MB991958 to data reading mode for following item.
^ Item 71: Lateral G-sensor
4. Confirm the indicated value. The voltage should measure as follows:
^ When vehicle is stationary (level): 2.4 - 2.6 V
^ When vehicle is being driven: 1.0 - 4.0 V
Q: Is the lateral G-sensor input normal?
YES: This malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope With Intermittent Malfunction.
NO: Go to Step 2.

STEP 2. Check the power supply circuit. Measure the voltage at lateral G-sensor connector D-37.





1. Disconnect connector D-37, and check at the harness side.
2. Turn the ignition switch to the ON position.
3. Measure the voltage between terminal 1 and ground. It should measure approximately 12 volts (battery positive voltage).
Q: Is battery positive voltage (approximately 12 volts) present?
YES: Go to Step 3.
NO: Go to Step 4.

STEP 3. Check the ground circuit. Measure the resistance at lateral G-sensor connector D-37.





1. Disconnect connector D-37, and check at the harness side.
2. Measure the resistance between terminal 3 and ground. It should measure less than 2 ohms.
Q: Is the resistance 2 ohms or less?
YES: Go to Step 8.
NO: Go to Step 6.

STEP 4. Check the following connectors.





^ Lateral G-sensor connector D-37





^ Junction block connectors C-211, C-214 Check the connectors for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Are the connectors and terminals in good condition?
YES: Go to Step 5.
NO: Repair it and then go to Step 11.

STEP 5. Check the following harness wire.








The wire between lateral G-sensor connector D-37 (terminal 1) and junction block connector C-211 (terminal 2)
Q: Is the harness wire damaged?
YES: Repair or replace it and then go to Step 11.
NO: Go to Step 11.

STEP 6. Check the following connectors.





^ Lateral G-sensor connector D-37





^ Intermediate connector C-122





^ ABS-ECU connector B-118 Check the connectors for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Are the connectors and terminals in good condition?
YES: Go to Step 7.
NO: Repair it and then go to Step 11.

STEP 7. Check the following harness wire.








The wire between lateral G-sensor connector D-37 (terminal 3) and ABS-ECU connector B-118 (terminal 24)
Q: Is the harness wire damaged?
YES: Repair or replace it and then go to Step 11.
NO: Go to Step 11.

STEP 8. Check lateral G-sensor output voltage.





1. Disconnect connector D-37, and then connect special tool MB991348 between terminals of the disconnected connectors.
2. Turn the ignition switch to the ON position.
3. Measure the voltage between terminal 2 and ground.
^ It should measure 2.4 - 2.6 volts when the lateral G-sensor is placed on a level plane.
^ Voltage should measure 3.4 - 3.6 volts when the lateral G-sensor is placed with its label positioned as shown.
Q: Is the lateral G-sensor output voltage normal?
YES: Go to Step 9.
NO: Replace the lateral G-sensor. Then go to Step 11.

STEP 9. Check the following connectors.





^ Lateral G-sensor connector D-37





^ Intermediate connector C-122





^ ABS-ECU connector B-118 Check the connectors for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Are the connectors and terminals in good condition?
YES: Go to Step 10.
NO: Repair it and then go to Step 11.

STEP 10. Check the following harness wire.








The wire between lateral G-sensor connector D-37 (terminal 2) and ABS-ECU connector B-118 (terminal 14)
Q: Is the harness wire damaged?
YES: Repair or replace it and then go to Step 11.
NO: Replace the brake modulator hydraulic unit (integrated with ABS-ECU). Then go to Step 11.

STEP 11. Recheck for diagnostic trouble code.





Check again if the DTC is set.
1. Turn the ignition switch to the ON position.
2. Erase the DTC.
3. Turn the ignition switch to the LOCK (OFF) position.
4. Turn the ignition switch to the ON position.
5. Check if the DTC is set.
6. Turn the ignition switch to the LOCK (OFF) position.
Q: Does DTC 71 reset?
YES: Start over at Step 1.
NO: The procedure is complete.