Inspection Procedure 7
Auto-cruise Control Indicator Light Inside Combination Meter Does Not Illuminate. (However, Auto-cruise Control Is Normal).Auto-cruise Control Indicator Light Drive Circuit Part 1:
Auto-cruise Control Indicator Light Drive Circuit Part 2:
CIRCUIT OPERATION
The power for the auto-cruise indicator in the combination meter is supplied from the ignition switch (IG1). When the auto-cruise control system is operating, the transistor inside the auto-cruise control-ECU illuminates the auto-cruise indicator through ECU terminal number 15.
TECHNICAL DESCRIPTION (COMMENT)
The cause is probably the malfunction of the indicator bulb or the malfunction of the connector or harness.
TROUBLESHOOTING HINTS
- Malfunction of the indicator bulb.
- Damaged harness or connector.
- Malfunction of the auto-cruise control-ECU.
DIAGNOSIS
Required Special Tool:
- MB991223: Harness Set
STEP 1. Check the auto-cruise control indicator bulb.
1. Remove the combination meter. (Refer to Combination Meter Assembly).
2. Check the auto-cruise control indicator bulb.
Q: Is the bulb blown?
YES: Replace the bulb. Go to Step 6.
NO: Go to Step 2.
STEP 2. Measure the signal voltage at auto-cruise control-ECU connector C-52 by backprobing.
1. Do not disconnect auto-cruise control-ECU connector C-52.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between auto-cruise control-ECU connector C-52 terminal 15 and ground by backprobing.
- The voltage should measure battery positive voltage.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage battery positive voltage?
YES: Check that the malfunction is eliminated. If the malfunction is eliminated, it can be assumed that this malfunction is intermittent. (Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction). If the malfunction is not eliminated, replace the auto-cruise control-ECU, and then go to Step 6.
NO: Go to Step 3.
STEP 3. Check combination meter connector C-29 and C-30, auto-cruise control-ECU connector C-52 and junction block connector C-84 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Are the connector and terminals in good condition?
YES: Go to Step 4.
NO: Repair or replace the faulty connector. (Refer to Harness Connector Inspection). Go to Step 6.
STEP 4. Check the combination meter.
1. Remove the combination meter and measure at the combination meter side. (Refer to Combination Meter Assembly and Vehicle Speed Sensor).
2. Measure the continuity between combination meter C-29 terminal 29 and combination meter C-30 terminal 13.
- The measured continuity should be less than 2 ohms.
3. Install the combination meter.
Q: Is the measured continuity less than 2 ohms?
YES: Go to Step 5.
NO: Replace the combination meter. (Refer to Combination Meter Assembly and Vehicle Speed Sensor). Go to Step 6.
STEP 5. Check the harness wire between auto-cruise control-ECU connector C-52 terminal 15 and junction block connector C-84 terminal 25 for damage.
Q: Is the harness wire in good condition?
YES: It can be assumed that this malfunction is intermittent. (Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction). Go to Step 6.
NO: Repair the damaged harness wire. Go to Step 6.
STEP 6. Check that the malfunction is eliminated
Q: Is the malfunction eliminated?
YES: This procedure is complete.
NO: Go to Step 1.