8206noco.fm Page 196 Thursday, July 2, 1998 1:19 PM
SYMPTOM RELATED DIAGNOSTICS ENGINE BRAKE VERBAL COMPLAINT (continued) Test 257
Test 512
Checking for engine brake disabling parameters
Checking for a failed relay
1. Using the engine speed control ON/OFF and SET buttons, set the engine speed to 1800 rpm. 2. Using a diagnostic tool (Pro-Link or PC), monitor the engine speed, fuel flow, throttle position and clutch switch status. 3. Turn the Speed Control ON/OFF switch to the OFF position.
As the engine decelerates, if the throttle position on the diagnostic tool indicates anything other than 0% throttle, there is a problem with the throttle pedal circuit. See Diagnostic Blink Code 5-2. As the engine decelerates, if the fuel flow on the diagnostic tool indicates anything other than 0 fuel above 900 rpm, remove the injection pump and send it to a certified pump shop for repairs. Retest to be sure the problem has been corrected. As the engine decelerates, if the clutch switch status on the diagnostic tool indicates that the clutch was disengaged at any time, there is a problem in the clutch switch circuit. Check the clutch switch adjustment. Also see the Switch Diagnostics section. If everything appears to be working properly, proceed to Test 514.
Page 196
1. Replace the engine brake relay with a new part and test the engine brake.
If the engine brake works properly, the old relay was bad and the new relay fixed the problem. Retest to be sure the problem has been corrected. If the engine brake does not work properly, the system appears to be electrically correct. Consult the E7 or E9 Service Manual for Dynatard troubleshooting procedures, or the Jacobs Brake Service Manual for Jake Brake troubleshooting procedures.
