Section 79.1
SPN 1072/FMI 4

This fault code indicates that the Jake Brake Stage 1 circuit failed low.‪

Check as follows:‪

1. Disconnect the front injector valve cover harness.
   
2. Measure resistance between pins 13 and ground on the front injector valve cover harness connector. If you are using J-48671–10 , measure either Jake 1 pin and ground.
   1. If the resistance is greater than 15 Ω, repair short to ground between pin 13 of the front injector valve cover harness connector and pin 66 of the 120–pin MCM connector. Refer to "79.1.1 Verify Repairs" .
   2. If the resistance is less than 5 Ω, go to the next step.
3. Remove the upper valve cover.
4. Disconnect the front Jake Brake.
5. Measure resistance between either terminal on the Jake Brake solenoid and ground.
   1. If the resistance is less than 5 ohms, replace the Jake Brake solenoid. Refer to "79.1.1 Verify Repairs" .
   2. If the resistance is greater than 5 Ω, repair the short to ground between pins 13 and 14 of the front injector valve cover harness and the Jake Brake solenoid. Refer to "79.1.1 Verify Repairs" .

Section 79.1.1
Verify Repairs

Verify repairs as follows:‪

1. Turn ignition OFF.
2. Reconnect any electrical connections that were disconnected to perform the diagnosis.
3. Clear codes with DDDL 7.0 or latest version.

   ENGINE EXHAUST ‪
   To avoid injury from inhaling engine exhaust, always operate the engine in a well-ventilated area. Engine exhaust is toxic.‪

4. Start and bring engine up to operating temperature (over 140°F/60°C).
5. Verify operation is satisfactory and no warning lamps illuminate. If warning lamps illuminate, troubleshoot the codes. If assistance is required, call the Detroit Diesel Customer Support Center at 313–592–5800.