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Discussion Starter · #1 ·
I just pulled my codes and 78 came up. MKIV.com says this is the fuel pump control signal? What does this mean?
 

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There is a problem with your fuel pump ECU circuit. Does your car crank? If not, jumper terminals B+ and FP on your data link connector underhood, and see if your fuel pump pressurizes. If not, make sure you don't have a short/open in the circuit, and if you don't then your fuel pump is bad (verify resistance on fuel pump as well.)
If your fuel pump is OK, then the problem is your fuel pump ECU. You can verify this by following the proper diagnosis described in the factory service repair manual (which should be everyone's first 'mod'.)

Good luck!
 

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Discussion Starter · #3 ·
Looks like I'll have to take a look at the service manual. I've had a problem that's been getting progressively worse. When it's hot outside (80+ deg) after driving for a while, when I come to a stoplight and idle the car will hesitate and sometimes just die. Most of the time it will crank back up, I give it gas and it will hesitate then go. But it's been getting worse, for example today the car kept shutting off and eventually wouldn't start. I had to let it sit for a good 30 minutes and cool. Started it back up it hesitated once, then worked fine. Anyone had this happen? What should the resistance on the fuel pump ecu and fuel pump itself be?
 
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