496 no start electrical issue
 

I cannot get my 2007 496 to start. The starter relay will not operate with the key. It will roll over if i cross the relay. I swapped relays and it does the same thing. I get 12 volts on the yellow/red to the relay from the key when using the battery ground. But if I check with the ground going to the relay i only get 7 volts. My mechanic buddy and I have tested the shift switch and neutral switch and they are good. We put a jumper from the ground stud on back of the motor to the relay ground and the motor would then roll over with the key. I never tried to start the motor with the jumper. From what we can tell without a wiring diagram the ground for the relay comes from the computer. I installed vessel view to the motor and have no fault codes. The motor ran great last year. I pulled it end of the year to change the rear motor mounts and have the fuel injectors flow tested. I just put the motor back in last week and been having this problem since.

Exactly how many volts is the battery? Less than 11.8 volts is not good. You may just want to try a fresh auto battery to verify.

Battery was at 12.7 when i put the motor in but is at 12.4 volts right now from working on lights and stereo. I get the 12.4 to the relay from the key.

Thanks for the call from the great white north. How did you make out ?

Thank you for listening to my issue I know your time is valuable. But the fuse was not my issue because it doesn't have one. I will be ordering one tomorrow for it. I will mention i found 5 volts on the black/yellow to the relay to good ground. I have 7 volts when I measure across the relay with the key on....that would be from the black/ yellow to yellow/black, which starts out as yellow red at the key. It changes color through the cannon plug. I get the 5 volts on the black/yellow to ground when I turn the key switch to on and to start. And I get just over 12 volts when I measure from the yellow/black key on to good ground.

Turns out it was my smart craft harness. I unplugged it when I pulled the motor last fall and set it on the bench . Its one plug on the top of the motor that branches off to a few smaller ones if you use smart craft, which I don't so none of the plugs go to anything. Well i plugged it back in just to try it and it rolled over lol. Primed the fuel system and she came to life after 8 1/2 months.

and thats why I said do not send me your pcm until you do some more testing because I had a feeling your issue was somewhere else. If I was all about the money I would of said sure send it in and Ill test and charged for all my testing time.. Glad you found the issue. And like I said voltage issues are usually on the owner but can cause problems elsewhere. Take care

The help and information you offer over the phone and on this website is very appreciated. If I do end up having problems with the pcm down the road you can be sure I will be sending it your way.