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Tech question 2007 Hyundai Sonata

Outlaw

TCG Elite Member
TCG Premium
Jul 24, 2009
19,609
16,068
Johnsburg
I picked up a 2007 Hyundai Sonata yesterday supposedly needing a fuel pump. Car was owned by a friends uncle. Was told his daughter was driving it, it shut off, was towed to a repair shop where he was told it needed a fuel pump. He decided to just sell it as is for pennies as it was a spare spare car and not needed. Of course it's never that easy. Replaced the pump still nothing.

Things I have done/tested with power probe.

-Replaced fuel pump.
-Checked continuity from power wire from pump to relay. good.
-Checked continuity from ground wire from pump. good.
-Checked relay and fuse for fuel pump. both good.
-Checked continuity from relay to ECU both pos and neg. good.
-If I put 12v to the fuel pump from the relay location with my power probe, the pump will turn on and the car will start.


Fuel pump is 4 post relay. I receive good power TO the relay from the battery, but when ignition on I only receive 2.5v from the ECU signal wire. I checked continuity as I said so I can reasonably eliminate any issues with the wiring to the ECU.

Next logical thing (in my mind) would be ECU is bad, yes? As far as I was told, the car was driving just fine and simply shut off. Also, if I buy a used ECU, what's it take to program it IF that is needed? I get conflicting answers on brand specific forums...

I feel like I'm at the point of having to "throw parts" at the car which I've never been a big believer in, an ECU also isn't a spark plug, and it's an expensive part to throw at the car if that's the route I need to take. Is anyone on here a tech/have access to AllData schematics for the wiring between the ECU and fuse block and any and all fuses that contribute to the ECU? Any help is appreciated!
 

bikrboy128

Some say.....
TCG Premium
Jul 15, 2007
12,878
11,502
Wheaton
07 with a 3.3 i assume?
looking at this, i'd be looking at the ECU fusible link/engine control relay
the two blue wires (14 off the junction block) go to the upstream O2 sensors. maybe one of those is feeding back?
eNlOI2d.jpg
 
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