Hey Guys,
My sons 2007 Jeep Liberty V6 won't start. It does nothing. The lights in the dash turn on like when you start it but nothing else. The fuel pump is turning on and the car is not setting off any codes. I tested the battery and it was in great shape (only a year old) and I even took it to Napa for them to test and it was the same results as mine. The starter is fine. I get no clicking or anything when I turn the key.
Any thoughts? Thanks
Dave
I hope yours fares better than my son's . His did that but was doing crazy stuff with the dash trouble lights, and it turned out to be the main computer was fried. We ended up scrapping it as it was too expensive to fix.
Thanks for the tidbit of info. :(
It's been running fine so I'm hoping it's something simple that someone here can help me with.
Computer switches the ground for the relay , might be the problem
Can you explain a little further please?
Could it possibly be the ignition relay??? Thanks
yes could be a bad relay in the power box
I just switched the starter relay with the wiper relay (they were the same) and nothing still the same result.
What's next?
What if you short the 2 heavy wires at the relay
Do you mean like this?
https://www.youtube.com/watch?v=aV-uAdftl7o
How do I know which ones to jump?
exactly , either the 2 largest terminals on the relay or if 3 terminals are in line & 1 faces across it will will be the odd one & the one opposite to it
Ok the good news is that after Chryco's suggestion of shorting the terminals where the relay was the car started right up.
Now what is that telling me? What do I need to replace? Thanks
Probably means the computer is not closing the circuit to ground the relay to allow the engine to crank over , check to see if the alt is charging , take a reading before starting & a reading running , it must be higher when running usually 13-8 -14.2 v at the battery running , 13.2 not running
But if the alt wasn't charging wouldn't the battery be drained? The battery is fully charged.
Brad was saying when his computer quit starting the vehicle the computer would also not power the alt , so no charge
Ok I'll test it thanks
Ok here were my readings:
No running - 12.24
Running - 13.74
Thoughts????
The alt is definatly working so the computer is doing that part although both readings are low side
So do I take the alternator out and have it tested at Napa as a double check or could it be something else? If you think it's something else where do I look next? Thanks
Alt is working , normal battery voltage should be 13.2 with no load & running 13.8-14.2
but if you had the key on while not running when testing it could be reading 12v range , the fact that it exceeded battery voltage at 13.8 shows it is working fine.
you have tested / swapped relays so that is not the issue .
There are 4 terminals on the relay , the 2 you shorted & the 2 to the left & right , likely 1 has constant power the other will ground through the computer , you need to test this , you could have switched power but unlikely , the ground circuit is the problem is my guess , you could run a pair of wires to a switch inside the vehicle , flip the switch & it would activate the start relay & over ride the computer that is not closing that circuit when you turn the key .
Need a schematic to determine what triggers the relay.... I doubt the PCM commands the relay that powers the PCM..... Now if it were the fuel pump relay then yeah the PCM commands the fuel pump on but the first relay controls the power to the PCM & I believe that is powered off the ignition switch......
Just knowing you can jump the relay & it'll run puts you well on your way, allot of stuff has been proven good...