Multiplex Communication System - Diagnostics: Diagnosis Toyota Sequoia I

HOW TO PROCEED WITH TROUBLESHOOTING

Perform troubleshooting in accordance with the troubleshooting flowchart.

Scheme 1

Scheme 2

Scheme 3

Scheme 4

Scheme 5

Scheme 6

Scheme 7

Scheme 8

Scheme 9

1. Diagnosis system: (Scheme 3), each ECU of this vehicle is connected by communication bus and it transmits each signal by communication. This communication bus is self-diagnosed by body ECU and it memorizes DTC when it detects communication stop to ECU or communication bus +B short or GND short. There is a possibility that body ECU cannot self-diagnose accurately unless it doesn't work normal. So, please note that troubleshooting of body electrical system should be done after confirming if body ECU and open door indicator work normally by following step - BASIC INSPECTION. If DTC of ECU communication stop is output, there is a possibility of connector disconnection or 2 communication buses open. It will not become abnormal with only 1 communication bus open. If 2 communication buses are open at the position (Scheme 5), DTC of ECU communication stop between those 2 buses is output.
2. Basic inspection: Inspect Body ECU NOTE: This inspection diagnoses body ECU CPU to determine if it works normally or not. Check body ECU operation. Check if the luggage compartment door opener works normal. OK: Go to next step "open door indicator light inspection". NG: Go to next step. Check rear wiper system (Except body ECU). See steps 4 and 9 of «INSPECTION»(/toyota/sequoia/i-2000-2004/remont/wiperwasher-systems/#wiper-system-washer-system). OK: Replace the body ECU. NG: Repair of replace malfunction part. Inspect open door indicator light NOTE: If open door indicator light is not turned on, DTC will not be output. Check open door indicator light. Check if open door indicator light is turned on when either door opens. OK: Go to next step, DTC CHECK. NG: Repair the open door indicator light. See «INSPECT OPEN DOOR WARNING LIGHT»(ref-174958-S31518023022005041300000).
3. DTC check (Using diagnosis check wire): Using SST, connect terminals "Tc" and "E1" of DLC3. SST 09843-18020 Turn the ignition switch ON. NOTE: As an example, the blinking patterns for codes; normal, 12, 11 and 12 are shown. (Scheme 8) Read the DTC on the open door indicator light. Check for the problem using the DTC table. (Scheme 10) After completing the check, turn the ignition switch off, and disconnect terminals "Tc" and "E1".
4. DTC CHECK (Using TOYOTA hand-held tester): Prepare the hand-held tester. Connect the hand-held tester to DLC3. Turn the ignition switch ON and switch the hand-held tester main switch ON. Use the hand-held tester to check the DTCs, note them down (For opening instructions, see the hand-held tester's instruction book.). See «HEADLIGHT DIMMER SWITCH CIRCUIT»(ref-174536-S07863904352005040800000) to confirm the details of the DTCs.
5. DTC clearance: DTC will be cleared when the trouble output to DTC is recovered normally.

DIAGNOSTIC TROUBLE CODES

Note. DTC 71 are not output through open door warning light on meter because of system itself. When some of the DTC 14, 15 is output, the DTC of other ECU communication stop is also output. In this case, please repair DTC 14, 15 first. The following shows DTCs which are output when +B or GND short occurs on communication bus. DTC 21-24, 51 and 52 does not mean switch abnormal but notifies how switch works. If DTC is not output when operating switch, it means failure of switch contact. If DTC is output when not opening switch, it means sticking switch.

If a malfunction code is displayed during the DTC check, check the circuit listed for that code in the table below (Perform the procedure given for that circuit).

Scheme 10

DIAGNOSTIC TROUBLE CODES (DTC) LIST

Scheme 11

Scheme 12

Scheme 13

Scheme 14

Scheme 15

Scheme 16

Scheme 17

Circuit Description

This DTC is output when communication stops Driver door ECU and body ECU.

Scheme 18

Inspection Procedure

Note. Before ECU replacement, see HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS to ensure all communication line/bus/wire issues have been eliminated as a cause of communication loss.

1. Check driver door ECU. Check if the driver door window glass auto up. NG: Replace the driver door ECU. OK: Go to next step.
2. Check wire harness. Preparation: Disconnect ECU connectors see scheme 20 For "B6" of body ECU (Scheme 12), "D22" of driver door ECU (Scheme 13), and "F18" of passenger door ECU (Scheme 14) Check Verify continuity between terminals MPX1 of body ECU and MPX2 of driver door ECU. Verify continuity between terminals MPX1 of driver door ECU and MPX2 of passenger door ECU. NOTE: If there is OPEN in wire harness of either a or b, please repair it. OK - there is continuity in wire harness of both a and b. NG: Repair or replace wire harness. OK: Replace the driver door ECU.

This DTC is output when communication stops between passenger door ECU and body ECU. see scheme 20

Scheme 19

Note. Before ECU replacement, see HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS to ensure all communication line/bus/wire issues have been eliminated as a cause of communication loss.

1. Check passenger door ECU. Check operation of passenger door window glass auto up. NG: Replace the passenger door ECU. OK: Go to next step.
2. Check wire harness: Preparation: Disconnect ECU connectors "D22" of driver door ECU (Scheme 13), "F18" of passenger door ECU (Scheme 14), and "B11" of back door ECU (Scheme 16) Check Verify continuity between terminals "MPX1" of driver door ECU and "MPX2" of passenger door ECU. Verify continuity between terminals "MPX1" of passenger door ECU and "MPX2" of back door ECU. NOTE: If there is an open in wire harness of either a or b, please repair it. OK: There is a continuity in wire harness of both a and b. NG: Repair or replace wire harness. OK: Replace the passenger door ECU.

Note. Before ECU replacement, see HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS to ensure all communication line/bus/wire issues have been eliminated as a cause of communication loss.

1. Check the communication circuit inside driver door ECU see scheme 20 Preparation: Disconnect the connector "D22" of driver door ECU (Scheme 13) Check the DTC. OK: Code B1214/14 or B1215/15 is not output. OK: Replace the driver door ECU. NG: Go to next step.
2. Check the communication circuit inside passenger door ECU. see scheme 20 Preparation Connect the connector of driver door ECU. (Scheme 13) Disconnect the connector "F18" of passenger door ECU (Scheme 14) Check the DTC. OK: Code B1214/14 or B1215/15 is not output. OK: Replace the passenger door ECU. NG: Go to next step.
3. Check the communication circuit inside back door ECU. Preparation Connect the connector "F18" of passenger door ECU see scheme 20 Disconnect the connector "B11" of back door ECU. (Scheme 16) Check the DTC. OK: Code B1214/14 or B1215/15 is not output. OK: Replace the back door ECU. NG: Go to next step.
4. Check the communication circuit inside combination meter ECU. Preparation Connect the connector "B11" of back door ECU (Scheme 16) Disconnect the connector "C6" of combination meter ECU. (Scheme 17)and see scheme 20. Check the DTC. OK: Code B1214/14 or B1215/15 is not output. OK: Replace the combination meter ECU. NG: Go to next step.
5. Check for short circuit between combination meter ECU and back door ECU. Preparation: Disconnect connector "B11" of back door ECU (Scheme 16) Check the DTC. OK: Code B1214/14 or B1215/15 is not output. OK: Repair or replace the wire harness between combination meter ECU and back door ECU see scheme 20 NG: Go to next step.
6. Check for short circuit between back door ECU and passenger door ECU. Preparation Connect the connector "C6" of combination meter ECU (Scheme 17)and see scheme 20. Disconnect the connector "F18" of passenger door ECU (Scheme 14) Check the DTC. OK: Code B1214/14 or B1215/15 is not output. OK: Repair or replace the wire harness between back door ECU and passenger door ECU see scheme 20 NG: Go to next step.
7. Check for short circuit between passenger door ECU and driver door ECU. Preparation Connect the connector B11 of back door ECU (Scheme 16) Disconnect the connector "D22" of driver door ECU (Scheme 13) Check the DTC. OK: Code B1214/14 or B1215/15 is not output. OK: Repair or replace the wire harness between passenger door ECU and driver door ECU. see scheme 20 NG: Go to next step.
8. Check for short circuit between driver door ECU and body ECU see scheme 20 Preparation Connect the connector "F18" of passenger door ECU (Scheme 14) Disconnect the connector "B6" of body ECU (Scheme 12) Check the DTC. OK: Code B1214/14 or B1215/15 is not output. OK: Repair or replace the wire harness between driver door ECU and body ECU. see scheme 20 NG: Go to next step.
9. Check for short circuit between body door ECU and combination meter ECU (W/O Sliding roof). Preparation Connect the connector "D22" of driver door ECU see scheme 20and "B6" of body ECU (Scheme 12) Disconnect the connectors of combination meter ECU (Scheme 17)and see scheme 20 and "B7" of body ECU (Scheme 12). Check: Wire harness between body ECU and combination meter ECU. see scheme 20 OK: Code B1214/14 or B1215/15 is not output. NG: Repair or replace the wire harness between body ECU and combination meter ECU. see scheme 20 OK: Replace the body ECU.
10. Check for short circuit between body ECU and combination meter ECU (W/Sliding roof). Preparation Connect the connectors "D22" of driver door ECU (Scheme 13)and "B6" of body ECU (Scheme 12) Disconnect the connectors "B7" of body ECU (Scheme 12)and "C6" of combination meter ECU (Scheme 17)and see scheme 20. Check the DTC. OK: Code B1214/14 or B1215/15 is not output. OK: Repair or replace the wire harness between body ECU and combination meter ECU. see scheme 20 NG: Go to next step.
11. Check for short circuit between body ECU and sliding roof ECU. Preparation Connect the connector "C6" of combination meter ECU (Scheme 17)and see scheme 20. Disconnect the connector "S18" of sliding roof ECU. (Scheme 15) Check the DTC. OK: Code B1214/14 or B1215/15 is not output. OK: Repair or replace the wire harness between body ECU and sliding roof ECU. see scheme 20 NG: Go to next step.
12. Check the communication circuit inside sliding roof ECU (W/Sliding roof). Preparation: Connect the connector "B7" of body ECU (Scheme 12) Check the DTC. OK: Code B1214/14 or B1215/15 is not output. OK: Replace the sliding roof ECU. NG: Replace the body ECU.

Note. Before ECU replacement, see HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS to ensure all communication line/bus/wire issues have been eliminated as a cause of communication loss.

Scheme 20

Scheme 21

1. Check wire harness. Preparation : Disconnect the connector of tuner and body ECU. Check Continuity between wire harness and body ground. OK : No continuity NG : Repair or replace the wire harness. OK : Go to next step.
2. Check body ECU. Preparation : Connect the connector of body ECU. Check the DTC. OK : B1242/42 is not output. NG : Replace the body ECU. OK : Replace the tuner.

This DTC is output when open or GND short of GSW terminal is detected.

Scheme 22

Scheme 23

Note. Before ECU replacement, see HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS to ensure all communication line/bus/wire issues have been eliminated as a cause of communication loss.

1. Check for open and short in wire harness and connector between body ECU and AIRBAG sensor assembly. NG : Repair or replace wire harness and connector. OK : Go to next step.
2. Check the body ECU. Check : If DTC B1243/43 is output after replacing body ECU. OK : B1243/43 is not output. NG : Replace the AIRBAG sensor assembly. OK : Replace the body ECU (Original body ECU is failure).

This DTC is output when failure of light sensor circuit is detected.

Scheme 24

Scheme 25

Note. Before ECU replacement, see HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS to ensure all communication line/bus/wire issues have been eliminated as a cause of communication loss.

1. Check light sensor using TOYOTA hand-held tester: Preparation Connect the TOYOTA hand-held tester to the DLC3. Turn ignition switch ON and TOYOTA hand-held tester main switch ON. Check the value of the illumination rate should change in the following range when the light sensor is put in the light or covered by a hand. OK: 0.8-22.0 ms. NOTE: 0.8-22.0 ms is the time required for light sensor to generate one cycle of frequency according to brightness. When not using TOYOTA hand-held tester. See step 7-13 of «INSPECTION»(ref-174834-S31294333462005041100000): NG: Replace the light sensor. OK: Go to next step.
2. Check wire harness and connector between light sensor and theft deterrent ECU. NG : Repair or replace wire harness or connector. OK : Replace the theft deterrent ECU.

This DTC is output when communication stops between combination meter ECU and body ECU.

Scheme 26

Note. Before ECU replacement, see HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS to ensure all communication line/bus/wire issues have been eliminated as a cause of communication loss.

1. Check combination meter ECU. Check: Start the engine and check that the speed meter and tachometer operate normally. NOTE: This inspection diagnoses the combination meter ECU CPU to determine if it works normally or not. NG: Replace the combination meter ECU. OK: Go to next step.
2. Check wire harness Preparation: Disconnect the connector "B11" of back door ECU (Scheme 16), "C6" of combination meter ECU (Scheme 17)and see scheme 20 and "B7" of body ECU (Scheme 12) Check Verify continuity between terminals "MPX1" of back door ECU and "MPX2" of combination meter ECU. Verify continuity between terminals "MPX1" of combination meter and "MPX2" of body ECU. OK: There is continuity in wire harness of both a and b. NOTE: If there is open in wire harness of either a or b, please repair it. NG: Repair or replace wire harness. OK: Replace the combination meter ECU.

This DTC is output when communication stops between sliding roof ECU and body ECU.

Scheme 27

Note. Before ECU replacement, see HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS to ensure all communication line/bus/wire issues have been eliminated as a cause of communication loss.

1. Check sliding roof ECU. Check that the operation of the sliding roof function is normal. NG: Replace the Sliding roof ECU. OK: Go to next step.
2. Check wire harness Preparation: Disconnect the connector "B7" of body ECU (Scheme 12)and "S18" of sliding roof ECU (Scheme 15) Check: continuity between terminals "MPX3" of body ECU and "MPX1" of sliding roof ECU. NOTE: If there is OPEN in wire harness, please repair it. OK: There is a continuity in wire harness. NG: Repair or replace wire harness. OK: Replace the sliding roof ECU.

This DTC is output when communication stops between back door ECU and body No. 1 ECU.

Scheme 28

Note. Before ECU replacement, see HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS to ensure all communication line/bus/wire issues have been eliminated as a cause of communication loss.

1. Check back door ECU. NOTE: This inspection diagnoses the back door ECU to determine if it works normally or not. Check that the operation of the back door function is normal. NG: Replace the back door ECU. OK: Go to next step.
2. Check wire harness. Preparation: Disconnect the connector "F18" of passenger door ECU (Scheme 14), "B11" of back door ECU and "C6" of combination meter ECU (Scheme 17)and see scheme 20. Check Verify continuity between terminals "MPX1" of passenger door ECU and "MPX2" of back door ECU. Verify continuity between terminals "MPX1" of back door ECU and "MPX2" of combination meter ECU. OK There is continuity in wire harness of both a or b. NOTE: If there is open in wire harness of either a or b, please repair it. NG: Repair or replace wire harness. OK: Replace the back door ECU.

See also:
• ABBREVIATIONS
• INSPECTION
• WINDOWS