68.3
TROUBLESHOOTING FLASH CODE 68
1. Turn vehicle ignition to the ON position. Refer to OEM guidelines.
2. Move TPS so counts are greater than 285.
3. Measure resistance between the ECM input (IVS) at the TPS and battery ground using
a volt-ohm meter.
[a] If the resistance was less than 100 , the idle validation input/switch is grounded or
defective. Contact OEM for repair procedure. Refer to section 68.3.7.
[b] If the resistance was greater than 100 , the fault condition no longer exists. No
further troubleshooting is required. Refer to section 68.3.7.
68.3.4
Check for Throttle Pedal Application
Perform the following steps to determine which type of TPS is being used:
1. Visually check to determine which throttle pedal has been installed that utilizes the IVS
function.
[a] If the throttle pedal has an idle validation switch installed, verify TPS count.
Refer to section 68.3.5.
[b] If the throttle pedal has no idle validation switch installed, update customer
calibration using a programming station. Change the settings from idle validation to
"No Function" and save changes. Verify repairs. Refer to section 68.3.7.
68.3.5
Determine Throttle Position Sensor Counts / Idle Validation Switch
Status
Perform the following steps to determine TPS counts:
1. Turn vehicle ignition to the ON position. Refer to OEM guidelines.
To avoid personal injury, before starting and running the
engine, be sure that the vehicle is parked on a level surface
and that the wheels are properly blocked.
2. Plug in DDR.
NOTE:
Vehicle need not be moving to determine TPS counts.
3. Compare idle validation switch status (switch light status) with the throttle position
sensor counts.
[a] If the IVS input is ON with the TPS count being less than 120, the problem no
longer exists. Refer to section 68.3.7.
All information subject to change without notice.
68-6
6SE497 9709 Copyright © 1997 DETROIT DIESEL CORPORATION
