Questions and Answers

Mitsubishi Galant DTC 12 Cruise Control Q. Hello Mr. Ciulla. Malfunctioned cruise control is a problem. When actuated, usual message displayed confirming that it is on. However, speed is not maintained. Local garage diagnostic was Code 12 - Speed Sensor. What am I to do before taking a $$$ trip to a dealer? 2000 Mitsubishi Galant 3.0 liter SOHC V-6 Automatic transmission 82,000 miles Fuel Injection ABS brakes P/S, A/C, Cruise control Rack and pinion steering Thank you in advance, Mike

A. This is how to troubleshoot DTC 12 Vehicle Speed Signal System.

CIRCUIT OPERATION:
This circuit checks the operation of the vehicle speed sensor.

When the vehicle moves forward and reverses, the sensor turns "ON " and "OFF " repeatedly.

DTC SET CONDITIONS:
The vehicle speed signals from the vehicle speed sensor are not input to the auto-cruise control-ECU when the vehicle speed is 40 km/h (25 mph )or more.

TROUBLESHOOTING HINTS:
The most likely causes for this code to be set are:

• Malfunction of the vehicle speed sensor.
• Damaged connector and harness.
• Malfunction of the auto-cruise control-ECU.

DIAGNOSIS:

STEP 1. Check the vehicle speed sensor.
Does the speedometer work?

If the speedometer is operating properly, go to Step 2.

If the speedometer is not operating properly, refer to Chassis Electrical - Combination Meter.

STEP 2. Check harness connector C-52 at the Auto-Cruise Control-ECU for damage. If harness connector C-52 is in good condition, go to Step 3.

If harness connector C-52 is damaged, repair or replace it. Check that a diagnostic trouble code is not output.

STEP 3. Check the harness wires between the Auto-Cruise Control-ECU connector C-52 and the vehicle speed sensor connector B-36.

If any harness wires between Auto-Cruise Control-ECU connector C-52 and vehicle speed sensor connector B-36 are damaged, repair or replace them. Check that a diagnostic trouble code is not output.

If the harness wires are in good condition, replace the Auto-Cruise Control-ECU. Check that a diagnostic trouble code is not output.

NOTE: After checking intermediate connectors C-17 and C-56, inspect the wire. If the intermediate connectors C-17 and C-56 are damaged, repair or replace them. Check that a diagnostic trouble code is not output.