Blue iQ No Crank, No Start Diagnostic Procedure

DSM.0039 Ver. 3.0 August 2, 2022
Parts Affected


Drive Away Protection (DAP) circuits #1, #2, #3, #4, #5



FMM door switch (box FMMs only)

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fuel receptacle cover

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fuel receptacle kill cap (remote fill panels)

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reed switch

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Crank Request circuit

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Start Confirm circuit

Diagnostic Overview
The Blue iQ Fuel System Control Module (FSCM) may prevent a start request if it detects that an FMM door, fuel receptacle
cover, reed switch, or auxiliary / remote kill cap is not connected. The FSCM does this by monitoring between 1 and 5
different DAP circuits for a ground signal indicating that the reed switch / kill cap are attached. If the FSCM detects an open
reed switch / kill cap, it will prevent a Start Confirm if a Crank Request is made.

Diagnostic Aids

A No crank, No start condition may be exhibited because of several possible reasons:
1.
2.
3.
4.
5.

Faulty DAP ground.
FSCM detects one or more DAP switches are open.
Fault in the OEM system preventing a Crank Request signal from being sent.
Electrical wiring issue.
FSCM internal fault.

NOTICE
Perform Initial Vehicle Check prior to proceeding.

Circuit / System Verification
Step 1

If Blue iQ gauge indicates “Starter Lockout—Fill Receptacle” or instrument cluster DAP lamp is illuminated, perform Initial
Vehicle Check.

Vehicle Started?
Yes – Return vehicle to service.
No – Proceed to Step 2.

Step 2



Ignition ON.
Check FMM low-pressure (LP) gauge and confirm the reading meets specifications for the vehicle.
NOTE: Refer to "Regular Output" on FMM faceplate or pressure PSI rating on the pressure regulator.

Pressure reading meets specification?
Yes – proceed to Step 3.
No – Pressure reading does not meet specification, reference Blue iQ Drivability Diagnostic Procedure.

Step 3



Ignition OFF.
Use a jumper wire to bypass Hexagon Agility starter interrupt control by jumping bulkhead connector chassis side
connector White/Red Pin 4 Crank Request circuit to Pink/White Pin 5 Start Confirm circuit.
NOTE: Reed switches on some systems are wired directly through OEM chassis wiring with a fuse and/or a relay
which must be jumped or checked.

Does engine crank?
Yes – Fault is in the Hexagon Agility system; proceed to Step 4.
No – Fault condition is in the OEM system; follow OEM diagnostics for a no crank condition.

Step 4
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
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Ignition OFF.
Disconnect Blue iQ harness FSCM connector.
Ignition ON.
Test for battery power on Blue iQ harness FSCM connector Cavities 31, 46, and 47.

Battery power present at each FSCM cavity?
Yes – Proceed to Step 5.
No – Repair open / high resistance in Battery + feed. Refer to Harness and Wire Repair Manual.

Step 5



Ignition OFF.
Test for battery ground on Blue iQ harness FSCM connector Cavities 6, 7, 8, and 9.

Battery ground present at each FSCM cavity?
Yes – Proceed to Step 6.
No – Repair open / high resistance in Battery ground circuit. Refer to Harness and Wire Repair Manual.
After repair is complete, proceed to Reassembly and Validation.

Step 6



Ignition ON.
Test for battery power on Blue iQ harness FSCM connector Ignition Signal circuit Cavity 37.

Battery power present?
Yes – Proceed to Step 7.
No – Repair open / high resistance in Battery ground circuit. Refer to
After repair is complete, proceed to Reassembly and Validation.

Step 7
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Ignition OFF.
Reconnect Blue iQ harness FSCM connector.
One at a time, methodically disconnect each reed switch connector / kill cap connector.
Use a jumper wire to jump from reed switch connector / kill cap connector DAP Signal Gray wire to a ground stud
or negative battery post.
Attempt to start engine.
Repeat above sub steps for all reed switches / kill caps.

Did vehicle start?
Yes – If fault is in a kill cap, refer to Kill Cap Diagnostic Procedure.
If fault is in a reed switch, proceed to Step 8.
No – Proceed to Step 10.

Step 8



Use a jumper wire to jump reed switch chassis connector from Cavity A to Cavity B of the suspect connector
circuit identified in Step 6.
Attempt to start engine.

Did vehicle start?
Yes – Inspect and repair suspect reed switch; refer to Reed Switch Assembly Diagnostic Procedure.
No – Proceed to Step 8.

Step 9



FSCM connector disconnected.
Measure resistance on the suspect DAP Return circuit as follows:
DAP #1 / #2 Return Cavity B of primary DAP connector and FSCM connector Cavity 5.
DAP #3 / #4 / #5 Return Cavity B of reed switch connector and FSCM connector Cavity 27.

Resistance between zero and 1 ohms?
Yes – Proceed to Step 10.
No – Repair open / high resistance in DAP Return circuit. Refer to Harness and Wire Repair Manual.
After repair is complete, proceed to Reassembly and Validation.

Step 10



Ignition ON.
Measure for voltage at each suspect DAP 5V Signal circuit chassis harness reed switch connector Pin A Gray
wire.
Voltage between 4.5 V and 5 V?
Yes – Replace FSCM.
No – Repair open / high resistance in 5V DAP Signal circuit. Refer to Harness and Wire Repair Manual.
After repair is complete, proceed to Reassembly and Validation.