What up people,

Does anyone know where I can find the schematic for the ECU printed circuit board. I am having an issue where my fuel pump does not prime when I turn the key in the on position. And I am forced to wait until my ECU gets into the mood to send power to my fuel pump. I wanted to follow the schematic to see if I could trace the problem to a cold soldered joint.

BTW Im runing a P06 ECU with a Neptune RTP Demon. I have been told that the fuel pump priming problem is being caused by poor soldering during the chipping process.

Thank you.

-Avery

 

Just to see... does the same thing occur when you power the Demon via USB?

 

I haven't tried that but I will and let you know.

 

How about checking the fuel pump relay?

 

sounds more like a main relay problem than an ecu problem. if all general troubleshooting fails, remove J1 in the ECU, if it clicks on, it's a solder or demon issue.

 

I have swapped main fuel relays but the problem still persists. Im chipping another ecu and putting my demon in it. This will hopefully solve the issue and also give me some more practice at chipping ecus

 

It's the ECU - common failure...

 

I tried plugging the demon unit up to the laptop to see if when powered by the laptop if it would put out the signal to prime the fuel pump but no results.

I took the top off of the ecu to view the status light on the demon and it was blinking slowly with one sec pulses. I tried to jiggle the demon unit and I noticed that the light started blinking faster until it started to look like a strobe light. It was at this point that it primed the fuel pump.

Im still not sure what the problem is but it looks like a poor connection somewhere. bump. could still use some help

 

Which part of the ecu is it?

 

did you remove J1 yet to test the stock ecu

 

I'll do that tomorrow and let you know. I'm mad tired from building shelves in my garage.

 

Just removed the J1 jumper and the problem still persisted. Looks like its a problem with the ecu and not the chipping job. Do you guys know which one of the components on the ecu could be causing this? bump

 

Bump

 

It's QM3 right below the injector drivers. If it's taking a long time to turn on then it's probably one of two things:
1.) QM3 is burning out from current overload, which might be an alternator issue or the ecu had water in it at some point. This is most likely.
2.) It's not getting enough current to reach threshold, which could be due to a pinched or grounded wire, a corroded connector or a damaged trace on the board which can be very difficult to find.

Try using the ECU in a different car to rule out wiring first.

 

I used a different ecu to rule out wiring already. When I put in a different virgin ecu the fuel pump primes right away.

 

bump

 

I don't know what you're bumping for, it's your ECU.
check for resistance on the traces to and from QM3. if you can't find any, replace QM3. or chip another ECU.
If you've never desoldered an old circuit board before, don't even think about trying to replace QM3. you will destroy the ecu.

 

I am bump ing the thread such that it can be move to the top so that more people can see it. Thank you for your input on the QM3. I have been very busy with work but as soon as I get a chance I will check the resistance to and from QM3 and replace if it there is a problem.