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Diagnosing Crank but No Start Caused by Faulty Junction Box Electronics (JBE) Failure

How to test and diagnose no start no spark caused by faulty JBE

 

In this video and article we discuss a no start no spark condition caused by a Faulty Junction Box Electronics (JBE) Failure. No Spark No Fault Codes Stored Condition. See how to diagnose step by step using a digital volt ohm meter (DVOM)

1 Working at the valve cover, disconnect the ignition coil electrical connectors

2 Turn the key ON with the Engine OFF

3 Check for battery positive voltage at coil terminal 3 – Green wire

Power is shared by all coils via splice X696

4 If battery positive voltage is not present, confirm fuse 10 in underhood fuse panel is intact and has battery positive volts. If fuse is intake and battery positive volts is present, check power at the DME

5 Locate DME connector X60004 terminal 1 Red / Green wire. Backprobe the connector at terminal 1, battery positive volts should be present. If no voltage is found at DME connector, relay K6326 function is checked next

6 Locate relay K6326 in the underhood fuse panel

7 Remove the relay and install a relay testing breakout. Install the relay into the testing breakout

8 Check for battery positive volts at relay terminal 3

9 If no voltage is present, the relay is Not being activated by the JBE

10 Check for relay coil control at relay terminal 6

11 If no relay control is found, the JBE is not activating the relay

12 To confirm the JBE is at fault, attach a temporary fused ground to relay terminal 6

13 Check for battery positive volts at ignition coil terminal 3 – green wire, if battery positive volts is now present, the JBE is at fault