Series 60 DDEC V Troubleshooting – Section 20.6 Diagnostic Request Switch Inoperative

Section 20.6
Diagnostic Request Switch Inoperative

Before using this procedure, all basic mechanical checks and physical inspections should have been performed with no problem found.‪

Section 20.6.1
Check Diagnostic Request Circuit

Perform the following steps to check the diagnostic request circuit:‪

1. Turn ignition ON; engine not running.
2. Plug in DDR.
3. Select Switch/Light Status.
4. Depress and hold diagnostic request switch.
5. Observe the Diagnostic Request Status on the DDR.
   1. If the display reads ON, refer to "20.6.2 Check Red Stop Lamp and Amber Warning Lamp Bulbs" .
   2. If the display reads OFF, the diagnostic request line (V-25) is open, or is not being grounded when the switch is depressed. Check the V-24 wire and ground for diagnostic request switch. Repair the problem; refer to "20.6.3.1 Verify Repairs" .
   3. If no diagnostic request on the DDR input list, the ECM/ECU is not configured for diagnostic request operation. Refer to the DDEC V Application and Installation manual, 7SA821.

Section 20.6.2
Check Red Stop Lamp and Amber Warning Lamp Bulbs

Perform the following steps to check the SEL/RSL and CEL/AWL bulbs:‪

1. Turn ignition OFF.
2. Remove CEL/AWL and SEL/RSL bulbs. Check to see if either is burned out or damaged.
   1. If the bulbs are okay, refer to "20.6.3 Check 12V / 24V Ignition Line" .
   2. If the bulbs are defective, replace the bulbs. Refer to "20.6.3.1 Verify Repairs" .

Section 20.6.3
Check 12V / 24V Ignition Line

Perform the following steps to check the 12V/24V ignition line:‪

1. Turn ignition ON.
2. Disconnect vehicle harness connector at ECM/ECU.
3. Measure voltage at cavity V-15.
   1. If voltage measurement is less than 11.5V, ignition fuse or circuit breaker is blown, and the ignition line could be open or shorted to ground.
   2. If the voltage measurement is greater than 11.5V, the circuit V-1 or V-2 is open. Repair the open. Refer to "20.6.3.1 Verify Repairs" .

Section 20.6.3.1
Verify Repairs

Perform the following steps to verify repairs:‪

1. Reconnect all connectors.
2. Turn ignition ON.
3. Press diagnostic request switch.
   1. If codes flash, the system is working. Repairs are complete. If any other problems exist, refer to "18.3 First Step for Diagnosing a Fault Within the DDEC System" .
   2. If the system does not function, all system diagnostics are complete. Review this section to find the error. Refer to "20.6.1 Check Diagnostic Request Circuit" .