Low Power on Injector harness

Chriscart · 09-18-2015, 07:40 PM

2009 Chevy Cobalt LT 2.2 L4 ecotec
Hi, good evening all. I am new to this forum and therefore not sure if this topic has been discussed, but here goes. I was driving yesterday when I noticed the coolant temperature was going up to 235 degrees when the traffic slows, so i kept turning of the engine whenever i stopped even for the shortest while. as soon as i could, i pulled off and went to check the radiator fan and realize it was spinning slower than it should, i toggled the connection a little and the speed improved but slowed again when i let go. after about 10 minutes driving the car just died; cranked but wouldn't start. I noticed that my power outlet was also dead. i got it towed home and today while inspecting it i noticed the ground cable that bolts on the transmission close to the fan was loose, i also realize that the sockets for the injectors only had 2.9 volts and after changing the outlet fuse, it opened again which leads me to think there is a short somewhere. any help will be greatly appreciated, pleeease!!...and thanks

Tech II · 09-18-2015, 09:22 PM

Well, did you clean tighten the neg battery cable?

Check the cable connections at the battery?

Was the alternator charging ok?

Is the battery fully charged?

If a voltmeter across the battery is near 12.6 volts, but your injector harness is only showing 2.9, there is a bad connection somewhere, causing the voltage drop....

More specific on that outlet fuse....what is the exact name/number of it?

Chriscart · 09-18-2015, 10:00 PM

It's 20 amp fuse for the cigarette lighter; one of those little plastic yellow ones. I changed the battery altogether. from ground bar to live pole in the fuse box i get a constant 11.6v. do you know the fuse that controls the injectors? then i could trace the current flow

Chriscart · 09-18-2015, 10:05 PM

no i didnt check the alternator, how would i do that without the car running? is there a way i can do that, let me know and i will try it

Tech II · 09-19-2015, 08:33 AM

What I meant, was the alternator light on before the car died, or does the I/P have a voltage gage, and did you notice it not starting?

The only thing on that outlet fuse is the cig lighter(could be defective), and two power outlets(console and dash)....double check a coin or something else has not fallen in.......

Exactly, how were you testing the voltage to the injectors?

Did you disconnect all four harnesses, and attach a test light to the pink/black wires at all four connectors? Light should be bright.......or did you use a voltmeter? Did you do this with key on and engine not running, or while cranking?

The injector fuse is in the underhood fuse block......it get's it's power from the powertrain relay......there is a bus bar between the fuse and the injectors.....

I would use a test light...this causes current to flow through the circuits.....

Key on, engine not running....Attach test light across the battery and notice the brightness.......now probe the inj fuse on both sides.....should be same brightness..... now probe the pink/black connector in each of the disconnected injector harnesses.....should all be the same brightness as the the brightness at the fuse.....if dimmer, then problem is at the power bus bar....

Crvett69 · 09-19-2015, 11:34 AM

have you tried jump starting the car to see if it will start? can also use run one of the jumper cable from battery - post to a ground point on the engine to see if your ground cable is working right

Chriscart · 09-19-2015, 06:29 PM

I tried jumping it but that did not work, I even took my new battery from my truck and put it in it. (it is still in there now) no the alternator light did not come on, only the check engine light. I checked the cig. lighter for continuity to see if there was a short but the circuit was open. I didn't check the second one, i assumed it was a parallel circuit) for the test of the injector harness i used a multi-meter tester set to DC current and and pinned the pink wires with the positive side while the other leg is clamped to a ground in the engine. the key was in the ON position for first test then i cranked for all. i then removed the pigtail attachment and checked the connection directly from the wire loom itself with the same result. Where is this bus bar i would like to carry out that procedure you mentioned as i will be working all night to resolve this situation, thanks

Tech II · 09-19-2015, 08:20 PM

Why in the world are you testing current on the injector harness?

You should be checking voltage like I suggested....for the life of me, I don't know how you didn't blow the fuse, unless there is a huge voltage drop in the circuit...

Chriscart · 09-19-2015, 08:43 PM

sorry my bad i checked voltage not current. the power train relay does engage when power is applied to it , i need to trace from there to see where the voltage drops. im now checking the individual pink and black lines that leaves the bottom of the fuse box to the injectors i am not sure what you refer to as the "bus bar" I understand the term in house electric but not car

Chriscart · 09-19-2015, 09:27 PM

THANKS A MILLION!!!! it started just now, it was the 15 amp injector fuse, i must have looked into that box 10 times and did not see that marking. Thanks very much though for bearing with me on this. im gonna go figure out the cig lighter issue now, i will post the result of that too

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