A typical diagnosis is a short to ground.
77.2.1
Short to Ground Check
Perform the following step to troubleshoot a short to ground.
1. Disconnect the CMP Sensor.
2. Measure the resistance between pin 1 of the CMP Sensor and ground. See Figure 77-2.
[a] If the resistance is greater than 5 Ω, go to step 3.
[b] If the resistance is less than 5 Ω, replace the CMP Sensor.Refer to section 77.2.1.1.
3. Measure the resistance between pin 2 of the CMP Sensor and ground.
[a] If the resistance is greater than 5 Ω, go to step 4.
[b] If the resistance is less than 5 Ω, replace the CMP Sensor.Refer to section 77.2.1.1.
4. Disconnect 120-pin MCM connector.
5. Measure the resistance across pins 1 and 2 of the CMP harness connector.
[a] If the resistance is greater than 5 Ω, go to step 6.
[b] If the resistance is less than 5 Ω, repair the short between pins 1 and 2 of the
CMP harness connector and pins 44 and 45 of the 120–pin MCM connector.
Refer to section 77.2.1.1.
6. Measure the resistance between pin 1 of the CMP harness connector and ground.
[a] If the resistance is greater than 5 Ω, go to step 7.
[b] If the resistance is less than 5 Ω, repair the short to ground between pin 1 of the CMP
harness connector and pin 44 of the 120–pin MCM connector. Refer to section 77.2.1.1.
7. Measure the resistance between pin 2 of the CMP harness connector and pin 45 of the
120–pin MCM connector.
[a] If the resistance is greater than 5 Ω, review steps 2 through 7. If the results are the
same, contact Detroit Diesel Customer Support Center (313–592–5800).
[b] If the resistance is less than 5 Ω, repair the short to ground between pin 2 of the CMP
harness connector and pin 45 of the 120–pin MCM connector. Refer to section
77.2.1.1.
