Inspection of Headlight Auto Leveling Control Module and Its Circuit (LED Headlight Model)
Precautions: Precautions for Headlight Auto Leveling System Service · Precautions for Body, Cab and Accessories · General safety (00)
Voltage and Signal Check
1)Remove headlight auto leveling control module (with connector connected). 
2)Check voltage and/or pulse signal using voltmeter and oscilloscope.
NOTE:
•Check that battery voltage is 12 V or more.
•Outputs from terminals marked with asterisk (*) cannot be measured with voltmeter because they are pulse signals. Use oscilloscope for measuring these outputs.
•Outputs from terminals marked with asterisk (*) cannot be measured with voltmeter because they are pulse signals. Use oscilloscope for measuring these outputs.
| [A]: | Headlight auto leveling control module connector (View: [a]) |
“E18” connector
| Terminal No. | Wire color | Circuit | Normal voltage | Condition |
|---|---|---|---|---|
| E18-1 | — | — | — | — |
| E18-2 | — | — | — | — |
| E18-3 | LT BLU | Left side headlight unit diagnosis signal circuit | Approx. 4.7 V |
•Ignition: “ON”
•Headlights: ON |
| Approx. 0 V | Other than above condition | |||
| E18-4 | BLU | Headlight ON signal | Approx. 0 V | Headlights: ON |
| Approx. 12 V | Headlights: OFF | |||
| E18-5 | — | — | — | — |
| E18-6 | — | — | — | — |
| E18-7 | — | — | — | — |
| E18-8 | GRN | Headlight leveling actuator signal circuit | 3.7 – 11.9 V | For about 17 seconds after turning on headlights with ignition “ON” |
| Approx. 0 V | Other than above condition | |||
| E18-9 | — | — | — | — |
| E18-10 | — | — | — | — |
| E18-11 | — | — | — | — |
| E18-12 | — | — | — | — |
| E18-13 | BLK | Headlight auto leveling control module ground circuit | Approx. 0 V | — |
| E18-14 | YEL | Headlight auto leveling control module power supply circuit | Approx. 12 V | Ignition: “ON” |
| Approx. 0 V | Other than above condition | |||
| E18-15 | RED | Headlight leveling actuator power supply circuit | Approx. 12 V | Ignition: “ON” |
| Approx. 0 V | Other than above condition | |||
| E18-16 | PNK | Headlight leveling actuator ground circuit | Approx. 0 V | — |
| E18-17 | — | — | — | — |
| E18-18 | — | — | — | — |
| E18-19 | — | — | — | — |
| E18-20 | LT GRN | Right side headlight unit diagnosis signal circuit | Approx. 4.7 V |
•Ignition: “ON”
•Headlights: ON |
| Approx. 0 V | Other than above condition | |||
| E18-21 | BLU | Rear vehicle height sensor signal circuit | 0.5 – 4.5 V | Ignition: “ON” |
| Approx. 0 V | Other than above condition | |||
| E18-22 | — | — | — | — |
| E18-23 | GRN | Rear vehicle height sensor power supply circuit | 5 V | Ignition: “ON” |
| Approx. 0 V | Other than above condition | |||
| E18-24 | GRY | Rear vehicle height sensor ground circuit | Approx. 0 V | — |
| E18-25* | RED | CAN communication line (high) | Refer to CAN communication signal. | |
| E18-26* | WHT | CAN communication line (low) | ||
Reference Waveform
Oscilloscope display
Shown below is typical waveform display provided by oscilloscope.
NOTE:
•Display includes the following types of data:
•Waveform varies depending on measurement condition and vehicle spec.
| [a]: | Waveform of channel 1 | [c]: | VOLT/DIV of each channel |
| [b]: | Ground level of each channel | [d]: | TIME/DIV |
CAN communication signal
CAN communication signal (High)
| Channel | Probe | Terminal No. |
|---|---|---|
| 1 | + | E18-25 |
| – | E18-13 |
CAN communication signal (Low)
| Channel | Probe | Terminal No. |
|---|---|---|
| 2 | + | E18-26 |
| – | E18-13 |
Measurement condition
•Ignition: “ON”
| 1. | CAN communication signal (high) |
| 2. | CAN communication signal (low) |