GLC Control Units
- The control unit may be tested with a voltmeter. Engine must be at operating temperature. For testing, ignition switch must be "ON" and engine not running. Measure voltage at each terminal and compare values to appropriate Control Unit Testing chart.
CONTROL UNIT TESTING
| Terminal | Connection | Voltage | Checking Condition |
|---|---|---|---|
| A | Ignition Signal | 12V | Ignition switch "ON" |
| B | Battery Power | 12V | Ignition switch "ON" |
| C | A/C Signal | 12V | A/C "ON" (all eng. speed) |
| D | Slow Fuel Cut Solenoid | 12V | At 2500 RPM w/ terminals m and o disconnected |
| E,I,n | - | - | Not necessary to check |
| F | Air/Fuel Solenoid | 0-12V | At idle speed |
| H | Throttle Positioner Solenoid | 12V | At 1700 RPM |
| K | EGR Solenoid | 12V | At 2500 RPM |
| M | ACV Solenoid | 12V | At idle speed |
| N,p,r | Ground | 0V | Ignition switch "ON" |
| a | O2 Sensor | 0-1V | At idle speed |
| b | O2 Sensor (Sealed) | 0V | Ignition switch "ON" |
| c | Water Temperature Sensor | 1.2V | At idle speed |
| d | Ground (Water Temp. Sensor) | 1.2V | Ignition Switch "ON" |
| j | Power Steering | 12V | Power Steering "OFF" |
| k-l | Vacuum Switch | 10V | Ignition switch "ON" |
| m | Neutral & Clutch | 0V | At idle speed |
| o | Idle Switch | 10V | At idle speed |
| q | Water Thermo Switch | 0V | At idle speed |