Older OBS to LS wire harness setup

[kewljay223]

sounds like your missing some... there should be like 5 grounds or so just from the harness alone.... most of them are in the back. they should be coming out of the harness with ring terminals on them so they can be connected to the bellhousing bolt studs. i know for sure there is the one down low up front on driver side....but you have two??? not sure what the second is..

yes thats a way of testing but it doesnt mean its a good ground. could be just enough to light up the bulb. you should use a meter and set it to the resistance setting and touch one lead to the neg batt and the other to whichever ground you wanna test. the meter should from 1 to 0. if you have numbers, that means that is resistance (ohms) between the two points. that means its a bad/dirty connection or there is a slight cut/pinch somewhere in that wire.

now what i just described is only testing the ground path to the battery and not the wire itself. sounds like you got a decent path on each point, but i really think your missing wires from the harness that go to the pcm. if i was you, i would crawl up in there and look down behind the motor for stray grounds dangling.

[droopyzda1]

Thanks guys !! I double checked the grounds and cleaned them up cause some of them did have paint. I used a multimeter and checked the ohms and theybwere all at 0.3. . She fired right up, but I had to manually accelerate it at the cable for it to stay running. It would shut off if I let go of it. Going to check the resistance of the MAF, TPS, and IAC valve. Maybe one of them is bad. Also what about the truck intake vacuum openings? Could that be a part of the issue? The opening in the back of the intake is connected to the brake booster, I have the original purge valve still in place but the emissions is deleted and reprogrammed that way. I have an opening on the top of the intake but I have a plug over it. I also have a plug on the fuel pressure regulator.

[Mickeymotormount]

The fuel pressure regulator senses engine vacuum to maintain fuel pressure under all engine load conditions. It must be hooked to the intake manifold. You should also have a manifold absolute pressure sensor on top of the manifold. If either of these two are missing, let alone both of them, you will have some running problems.

[droopyzda1]

Thanks mickey !! Sure enough, there wasn't a MAP sensor connected, period !! It was an open hole on top in the back of the intake. I hooked up the scan tool to the obd2 connector and it verified it. I bought one and put it in, but there isn't a plug for it on my harness. I may have taken it out when I redid the harness, but I do not see it in the box where I put the wires that I took out. I will double check tomorrow. Now it starts but I just have to hold the accelerator for a few seconds, let go of it and it idles by itself. Thanks mickey also for the part number of the serpentine belt u used. I got the same one and it works like a charm. I just have to remove some washers I placed behind the custom a/c bracket cause it about 1/4 to far forward and doesn't line up with the other pulleys. I used the 5.3 upper and lower hoses and just trimmed them a bit to fit on the original C1500 radiator. Thanks again everyone, almost done, now all the finishing touches ar3 left.

[Mickeymotormount]

Glad to hear you found the problem. Hopefully the plug for the MAP sensor was overlooked and is still lurking somewhere in the harness.