Very long back story as to why I am looking to this answer.... Short Version: Does the ECU send the 12v to the contact side of the fuel pump relay (under dash), if not where does the 12v come from?


Slightly longer version is along these lines...

Car is an 01 with a TDR Rotrex kit, I am running Fuel and Timing cards currently. I went to pick up the MS3pro and some other goodies last week and drove the car, I stopped in at a Dollar General for a drink and came out to a crank and no start situiation (ran perfect prior to this). I had my wife pick me up, trailered the car back to my shop and put it up on the lift. What I have determined is that fuses and relays are good, EGI main and Main fuse, CAS/CPS are good, I still get no spark and no fuel. I do not feel the FP relay energize when I crank the car, I only could feel it energize when I jumped the DIAG box and turned the key on. I decided to check voltage at the connector/relay and I found that I have coil voltage to energize the relay but no 12v on the contact side.

I also do not get the TDR fuel and timing cards to light up when I turn the ignition to ON like they used to. I confirmed with Dan @ Track Dog Racing and he said when the key is ON the fuel and timing cards will do a little dance with the LED's.

This is leading me to believe something in the ECU has $hit the bed. From what I have read it seems that the immobilizer should let the car start for a short period of time before it dies, but I am wondering if it would completly shut everything down. So brings me back to the ECU, I am about to remove the fuel and timing cards and see if the car will fire which would point to the fuel and timing cards PNP harness or pins having an issue but if it does not start I am back to ECU.

Yes I could swap in the MS3pro but what if I had a chaffed wire that cooks the MS3pro as soon as I power it up? I need to check out the wires.

Lastly I wanted to say a couple other things that came to mind as I have been talking to myself outloud and to others.

1st - Two days before the Crank No start condition I had the battery light come on while running and driving (battery is good). I didnt think much of it because I had a new altenator on the shelf anyways and I was still seeing 14v on the OBD dongle via Torque Pro. However its the small things that make you question everything. By the way, I did replace the altenator and still no start.
2nd - When I walked to the car from the Dollar General, I had just unlocked the door with the key (because the FOB didnt work) and I dropped the FOB and keys on the concrete....The FOB came apart but I put it back together real quick. I then realized the FOB actually now worked, and would lock and unlock the doors!! Thought that was groovy, just drop it and its fixed. LOL However the car would NOT start. Very weird timing but It makes me think the key and immobilizer are coming into play. But how, its a chip with a reader in the ignition to read the code. How would dropping it cause a no start issue? Likely not related but the timing was really weird.


Sooo as I go along troubleshooting I was curious where the 12v, (to the contact side of the FP relay) came from. Because she has no juice, and if it is the ECU then I am leaning more the way of a really odd ECU failure.

It seems ECU failures are not too common but I do have some bad luck and the car is named Morticia.

Thanks to anyone who may read this and has any information to help me troubleshoot or prevent the demise of the new MS3pro I want to install.

-T

 

Tldr, no the ECU is open drain output, wht/Blu from main relay to pump, blk/wht from engine fuse for coil

Mellens wiring diagram is available for download

 

I have blu/red from relay to pump. The wht/blu appears to come from ECU connectors. I just tested voltage on the wht/blu with diag box jumped and I seem to get coil side to close the contacts but wht/blue from ECU reads 6/10 of a volt. Wondering if the ECU has really died. I found no loose grounds or chaffed wires, just wanted to make sure I was not going to smoke the MS3 when installed.

Black ground at the FP connector tests well with no resistance to chassis ground. So it appears to me the we are not getting 12v to the pump via ECU. Any thoughts if the voltage regulator would die in the ECU? I did have the battery light come on a couple days before this, but batteryt was good and also now has new altenator from Moss.

ETA: Ill look for the wiring download

 

wht/blu is sourced from the main relay, not the ECU

 

Thank you for the information. I have spent several hours yesterday reading and testing. Found some good pinouts and I am going to create a new thread based on what I have found. Even thought the main relay closes contacts and I have bench tested it I seem to think I have an issue with 12v on pin 4AF, (no 12v)