DDEC TROUBLESHOOTING
3. Measure resistance between cavity A and E of the SNEF module connector.
[a] If the measured resistance is less than 1,000 , the wires are shorted to each other.
Repair the wires and refer to section 66.3.9.
[b] If the measured resistance is greater than 1,000 , refer to section 66.3.6.
66.3.6
Check for Ground
Perform the following steps to check for a ground:
1. Measure resistance between cavity D and battery ground.
[a] If the measured resistance is greater than 1,000 , the ground wire is open. Repair
the open and refer to section 66.3.9.
[b] If the measured resistance is less than 1,000 , replace the SNEF module and
refer to section 66.3.9.
66.3.7
Check for Short to Ground
Perform the following steps to check for a short to ground.
1. Turn ignition OFF.
2. Remove jumper wire.
3. Disconnect the engine harness connector.
4. Measure resistance between cavity A of the SNEF connector and a good ground.
[a] If the measured resistance is less than 1,000 , the signal wire (#976) is shorted to
battery (-). Repair or replace the wire and refer to section 66.3.9.
[b] If the measured resistance is greater than 1,000 , replace the knock sensor and
refer to section 66.3.8.
66.3.8
Check for Signal Open
Perform the following steps to check for a signal open.
1. Insert jumper wire between E and C of the SNEF module connector.
2. Unplug the engine sensor harness connector.
3. Measure resistance between L2 (#976) and X1 (#573).
[a] If the measured resistance is greater than 1,000 , wire #976 is open. Repair or
replace the wire and refer to section 66.3.9.
[b] If the measured resistance is less than 1,000 , refer to section 66.3.4.
66.3.9
Verify Repairs
Perform the following steps to verify repairs.
All information subject to change without notice.
6SE497 9709 Copyright © 1997 DETROIT DIESEL CORPORATION
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