FL60 w/ISB 230? - Fuel pump relay code

[Smokey73]

I got a '99 FL60 w/ an 5.9 ISB. 9 of 10 times you crank it up, both engine lights come on and it throws code 373 and the throttle acts erraticly, or just the check engine light wiil come on and it throws 377. I'm guessing both codes are related to the fuel pump relay, but where is it? The last guy to drive this truck also ran a wire from a switch on the dash to the top of the injection pump and it won't start unless you flip the switch. Any ideas?

 

[Smokey73]

...

 

[Smokey73]

BTT

 

[Smokey73]

BTT

 

[Goofyexponent]

PM BigRigTech...he is certified in cummins engines. If he can't tell you what the problem might be, You're best off taking it to a shop.