Traction Control: Diagnosis Lexus RX I

DIAGNOSIS & TESTING

Note. DO NOT start engine when accessing diagnostic codes.

RETRIEVING DIAGNOSTIC TROUBLE CODES

1. Turn ignition switch to ON position. Ensure TRAC OFF indicator light illuminates for 3 seconds and turns off. If TRAC OFF indicator light does not function as indicated, see «TRAC OFF INDICATOR LIGHT, TRAC CUT SWITCH CIRCUIT»(ref-4501-S11902220532000063000000) under SYSTEM TESTS.
2. Ensure ignition switch is in ON position. If a DTC is set after TRAC OFF indicator light has illuminated for 3 seconds, light will begin blinking every 1.5 seconds. If DTC 53 is set, TRAC OFF indicator light may remain on (without blinking) until engine is started.
3. Using a fused jumper wire or service connector (SST 09843-18020), connect terminals Tc and E1 of Data Link Connector No. 1 (DLC1) or Data Link Connector No. 2 (DLC2). (Scheme 18) DLC1 is located in left side of engine compartment, next to strut tower. DLC2 is located under left side of instrument panel.
4. If a malfunction is detected, TRAC OFF indicator light will begin to flash a 2-digit DTC after 4 seconds. TRAC OFF indicator light will flash first digit, followed by a 1.5 second pause, and then light will flash second digit.
5. Count number of flashes to obtain digits of 2-digit code. If 2 or more codes are stored, a 2.5 second pause will separate codes. If 2 or more malfunctions are indicated at the same time, lowest numbered DTC will be displayed first. See «DIAGNOSTIC TROUBLE CODES»(ref-4501-S10524153512000063000000) table.
6. If ABS is functioning properly, a normal code will be set. During normal code, 2 seconds will elapse, and then TRAC OFF indicator light will blink once every.25 second.
7. If TRAC OFF indicator light does not illuminate, see «Tc TERMINAL CIRCUIT»(ref-4501-S35324104832000063000000) or «TRAC OFF INDICATOR LIGHT, TRAC CUT SWITCH CIRCUIT»(ref-4501-S11902220532000063000000) under SYSTEM TESTS. After replacing or repairing malfunctioning components, clear diagnostic trouble codes. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-4501-S16447324812000063000000). Turn ignition off. Remove fused jumper wire or Service Connector (SST 09843-18020) from DLC1 or DLC2.

Scheme 18

DIAGNOSTIC TROUBLE CODES

CLEARING DIAGNOSTIC TROUBLE CODES

Note. Disconnecting negative battery cable will not clear diagnostic trouble codes.

Turn ignition on. Using a jumper wire or service connector (SST 09843-18020), connect DLC1 or DLC2 terminals Tc and E1. (Scheme 18) With vehicle stopped, depress brake pedal 8 or more times within 5 seconds. Ensure TRAC OFF indicator light indicates normal code. Remove jumper wire or Service Connector (SST 09843-18020).

DTC 43: ABS CONTROL SYSTEM MALFUNCTION

Note. For circuit identification and wire colors, see WIRING DIAGRAMS .

Circuit Description

DTC is set when ABS control system is malfunctioning. Possible cause is ABS control system.

Diagnosis & Repair

Determine if ABS DTCs are present. See ANTI-LOCK - SC300 & SC400 - WITH TRACTION CONTROL article. Repair ABS system as needed. If no DTCs are present, inspect circuit between ABS/TRAC ECU and malfunction indicator light.

DTC 44: NE SIGNAL CIRCUIT MALFUNCTION

Note. For circuit identification and wire colors, see WIRING DIAGRAMS .

ABS/TRAC ECU receives engine speed signals from Engine Control Module (ECM) on NE circuit. DTC is set when there is no NE signal input to ECM after traction control is initiated for .24 second. Possible causes are

1. Open Or Short In NEO Circuit
2. ECM
3. ABS/TRAC ECU

1. Turn ignition off. Check for open or short in Pink/Blue wire between ECM and ABS/TRAC ECU. Repair circuit as needed. If circuit is okay, go to next step.
2. Turn ignition on. Backprobing, measure voltage between ground and ABS/TRAC ECU connector A21 terminal No. 15 (Pink/Blue wire).
3. With ignition switch in ON position, 3-6 volts or less than one volt should exist. Turn engine on and allow to idle. With engine idling, 3-6 volts or less than one volt pulse should exist. If voltage is as specified, go to next step. If voltage is not at specified, replace ABS/TRAC ECU.
4. Clear codes. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-4501-S16447324812000063000000) under DIAGNOSIS & TESTING. Retrieve DTCs. If DTC 44 is still present, check condition of connectors. Repair as needed.

DTC 51: ENGINE CONTROL SYSTEM MALFUNCTION

Note. For circuit identification and wire colors, see WIRING DIAGRAMS .

If an engine DTC is present, TRAC system is prevented from functioning. DTC is set when problem signal is detected in engine control system with engine speed of 500 RPM or more for 7 seconds. Possible causes are

1. Engine Control System

Determine if any engine DTCs are present. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. Repair as needed. If no engine DTCs exist, inspect malfunction indicator light circuit.

DTC 52: BRAKE FLUID LEVEL WARNING SWITCH CIRCUIT

Note. For circuit identification and wire colors, see WIRING DIAGRAMS .

Brake fluid level warning switch sends appropriate signal to ABS/TRAC ECU when brake fluid level becomes low. DTC is set when ABS/TRAC ECU detects 1.5 volts or less on terminal LBL- for 10 seconds or more. Possible causes are

1. Brake Fluid Level
2. Brake Fluid Level Warning Switch
3. Brake Fluid Level Warning Switch Short Circuit
4. ABS/TRAC ECU

1. Inspect brake fluid level. If brake fluid level is low, check brake system for fluid leakage. If brake system is okay, adjust fluid level as needed. If fluid level is okay, go to next step.
2. Inspect brake fluid level warning switch. Continuity should exist between switch component terminals when switch float is down. Replace as needed. If switch is okay, go to next step.
3. Inspect brake warning light circuit between switch and ABS/TRAC ECU for open or short. Repair as needed. If circuit is okay, replace ABS/TRAC ECU.

DTC 53: ECM COMMUNICATION CIRCUIT MALFUNCTION

Note. For circuit identification and wire colors, see WIRING DIAGRAMS .

TRC circuits sends TRAC control information from ABS/TRAC ECU to Engine Control Module (ECM). ENG+ and ENG- circuits send engine control information from ECM to ABS/TRAC ECU. DTC is set when ECM receives a trouble signal in TRC circuit, or no ENG circuit data is received from ECM when engine speed is 500 RPM or more and vehicle speed is 37 MPH or more for 5 seconds. Possible causes are

1. Open Or Short In TRC Circuit
2. Open Or Short In EFI+ Circuit
3. Open Or Short In EFI- Circuit
4. ECM
5. ABS/TRAC ECU

Ensure ignition is off. Check continuity of TRC, EFI+ and EFI- circuits between ECM and ABS/TRAC ECU. Ensure circuits are not shorted to ground. Repair as needed. If all circuits are okay, replace ECM or ABS/TRAC ECU, or both.

SLIP indicator light blinks during TRAC operation. TRAC OFF indicator light is used for displaying DTC and indicating malfunction.

Inspect SLIP (TRAC) indicator light. Replace as needed. If light is okay, check for short circuit in wiring harness between ABS/TRAC ECU and SLIP (TRAC) indicator light. Repair as necessary. If circuit is okay, replace ABS/TRAC ECU.

Turn ignition on. Check voltage between terminals Tc and E1 of DLC1 or DLC2. (Scheme 18) If 8-14 volts is present, circuit is okay. ABS/TRAC ECU may be faulty if TRAC OFF indicator light does not blink when connecting a jumper wire between terminals Tc and E1. If 8-14 volts is not present, check for open or short circuit between ABS/TRAC ECU, DLC1 and DLC2, and ground. If circuits are okay, replace ABS/TRAC ECU.

When TRAC cut switch is pushed on, TRAC control goes off and TRAC OFF indicator light illuminates. TRAC OFF indicator light blinks when malfunction occurs and for displaying DTCs.

1. Determine if any ABS DTCs are present. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-4501-S36771809182000063000000) under DIAGNOSIS & TESTING. Repair as needed. If no DTCs exist, go to next step.
2. Remove TRAC cut switch (TRAC OFF switch). Disconnect harness connector. Check continuity between terminals No. 3 and 6 on switch connector. (Scheme 19) Continuity should only exist when switch button is pressed. Replace switch as needed. If switch is okay, go to next step.
3. Check continuity of CSW circuit between TRAC cut switch and ABS/TRAC ECU. Repair as needed. If circuit is okay. Inspect TRAC OFF indicator light. Replace as needed. If light is okay, go to next step
4. Check continuity of WT circuit between TRAC OFF indicator light and ABS/TRAC ECU. Repair as needed. If circuit is okay, replace ABS/TRAC ECU.

Scheme 19