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Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 8812
Experience:  I am ASE Master Truck Certified.
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Truck is a 2004 FL with C7 Cat, engine cranks but won't

Customer Question

Truck is a 2004 FL with C7 Cat, engine cranks but won't start. After several tries it will start, run for 5 to 10 minutes, and then shut off as if you turned the key off. I have replaced the timing sensors, the IAP sensor, fuel and oil pressures are ok. When the engine is running I get 5 volts on top of fuel pump. when the engine won't start I get 0 volts on top of the fuel pump. I checked the ECM and have +12 volts on pins 48 to 61, 52 to 63, 53 to 65, 53 to 67, and 70 to 63. I do not have access to Cat ET but I did pull the following flash codes using the cruise control; 12, 15, 18, 25, 29, 39, 72, 73, and 74. I have checked the key switch and all fuses and relays.
JA: Sometimes things that you think will be really complicated end up being easy to fix. The Heavy Truck Mechanic I'm going to connect you with knows all the tricks and shortcuts. Is there anything else the Heavy Truck Mechanic should be aware of?
Customer: Not that I can think of.
Submitted: 11 months ago.
Category: Medium and Heavy Trucks
Expert:  Cat Man replied 11 months ago.
Thanks for asking your question. I will try and help you out.
Unfortunately I have seen this problem many times.
Codes 72 73 and 74 are injector circuit fault codes. Whenever I have a C7 that has all these and will not start or runs for a short time. The injector driver module in the ECM has failed. I've seen many times.
Unfortunately the module can not be replaced. The ECM will need to be replaced. I am sorry. I wish I had better news.
Please reply back if you need more help or have more questions. I am happy to assist.

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