98 K2500, 5.7 to 5.3

[bowtieguy79]

are you speaking of C100 pin C and pin N? I had this same question on my 05 swap in the 94 K1500. I don't have these attached on my 94, but kind of wonder if they feed power from the in cab fuse block of the 05 back to the Heated circuit on the O2's?

Nice fuel lines btw

[Zukikev]

Yeah sorry I mean C and N and they are both Ignition 3 voltage. I found an ignition 3 in my 1998 C100 (D8)? I was mostly curious what it actually is.

I think I have figured out why my temp gauge wasn't working.. I sold my vortec heads, and I think the SENDER (1 DK GRN wire) stayed in the heads. I tapped my LS heads and installed the SENSOR. I then hooked up the wires (black and yellow, smaller connector than sender) which obviously didn't work because the SENSOR sends the ECT to the ecm, while the SENDER sends to the gauge.. I haven't done much work on sbc stuff, Gen I or Gen III, so this is all a learning process for me.

My fuel gauge doesn't work either. This should be dead simple... No?
C1 pin 9 is a purple wire says fuel gauge.
C3 pin 13 is purple/white says fuel level module.
Connect them. Nothing. Did I miss a ground? Miss the boat entirely?
Diagram below.

TCC brake switch. Purple wire, circuit 420. It is spliced off to the cruise control module, so I took it from there. That should work right? I haven't been able to throw a test light on it to verify that it shows 12v until the brake pedal is pressed. The Alldata diagram is below for reference.

Also, in my c100 from the GenIII pcm, pin J that is suppsed to be BLK/WHT is actually Blue. I haven't asked Nelson about this yet, just wondering if anyone knows.

[bowtieguy79]

Yeah sorry I mean C and N and they are both Ignition 3 voltage. I found an ignition 3 in my 1998 C100 (D8)? I was mostly curious what it actually is.

My fuel gauge doesn't work either. This should be dead simple... No?
C1 pin 9 is a purple wire says fuel gauge.
C3 pin 13 is purple/white says fuel level module.
Connect them. Nothing. Did I miss a ground? Miss the boat entirely?
Diagram below.

TCC brake switch. Purple wire, circuit 420. It is spliced off to the cruise control module, so I took it from there. That should work right? I haven't been able to throw a test light on it to verify that it shows 12v until the brake pedal is pressed. The Alldata diagram is below for reference.

Also, in my c100 from the GenIII pcm, pin J that is suppsed to be BLK/WHT is actually Blue. I haven't asked Nelson about this yet, just wondering if anyone knows.

Your fuel gauge, there should be a connector some where around the fire wall on the drivers side with fuel sending unit wires. Unplug it there and ohm it out, from the looks of the diagram your on the right track.
For TCC that should work.

[Zukikev]

Well, truck runs and drives, FINALLY. What an arduous road.

The truck would go through phases where it would fire right up and run great, or not fire at all. I thought it was a pcm connection issue. Tried a different pcm and it both ran and did not run with the new pcm.

Made sure my grounds were up to snuff.
Batt to frame,
batt to engine
engine to fender
pcm grounds to fender (about 12" away from the other engine to fender ground. Both connected to same steel bracket)
starter to frame
plus all the black and black/white ring terminal wires.

So then I checked the fuel pressure. 60psi when cranking, 53 psi for a 10 minutes after that when I pulled the gauge off. So my hypothesis that maybe my injectors were bleeding down into cylinders was shot. Changed FPR anyways.

It still wouldn't start after changing the FPR. Checked a plug, and it was soaked, of course. About 10 minutes later I tried the key and it fired right up! There goes my "its too flooded" hypothesis for why it wasn't starting at times. It started very well for about 4 or 5 days after that. Continued reassembly and went to pull it out of the garage to work on a different project, wouldn't start. \

We fooled around with it the next week and it was running well again. I went to take it for a test drive and it died half a block away. The pedal wasn't responding and at times wiggling the pedal or the wires would help, so I replaced the pedal and harness going to the pedal. Wouldnt start at all. By this point I was missing my exhuast appointment.

Back to google I went. Most of the 'no start 5.3' hits on google are related to not cranking over, rather than cranking over and not firing. I found one post, ONE mention, that the pcm grounds should go to the head (mine go to fender remember, and there is a fender to engine groud 12" away...). What have I got to lose though. So I hook booster cables to both the pcm body and the pcm ground bolt and stick them on the head. ...and it fired right up like nothing was ever wrong.

So when we say these engines are picky about their grounds, we MEAN it.

So I unloaded the bed (full of junk from the swap), changed oil again, and hit the road. Drove 130km at 115km/h, no problem.

Questions:

My fuel gauge doesn't work. I read that the fuel gauges are grounded through the pcms on these trucks, so I found the ground wire for it and grounded it. Now it just dances from 3/4 to above full. I believe the fuel gauge was working in the truck previous to the swap.

VSS: I have my purple VSS (VSS high) wire. It is a twisted purple and green wire with foil in an extra sheath around it. It is going to both the VSS wire in the 5.3's C100 and the speedo in the 98. This must not be right? I don't have the diagrams in front of me otherwise I would be more specific.
Is the VSS wire in the 5.3's C100 an input (from the VSS) or just an output (for the speedo)?

I haven't looked into getting my 4x4 working yet. Is there a signal from the pcm to the front actuator? Or should it just work based on the old 98's harness?

I'm mostly confused about the VSS, because I thought I had done it right based on what I had read here. Any help on these matters is greatly appreciated!

The truck sounds great with the FloPro V Force dual chamber muffler. It is dual 2.25 in and a factory 454 truck 3" tailpipe.

[Zukikev]

Got it all figured out.

There is a VSS extension that runs from the tranny to the tcase output that was still plugged in to 98 wiring. Plugged that in my speedo worked but my transmission still only had limited functionality (TC locked instantly as soon as I was moving, limited gears, etc). As I did more reading, I realized that the wiring and controls for the 4l80e are different and my pcm was still thinking it was controlling a 4l60e.

Here is the wiring differences between 4l60e and 4l80e:
http://www.performancetrucks.net/for...d.php?t=413157

The 4l60e doesn't have an ISS, and wires S, T, and U need minor changes. Nelson had done this when I sent my harness to them. What I had to do was find a tune from a 4l80e truck with the same OS ID as mine, and send it to HPT and have them do a segment swap.

Slow67 on ls1tech has also developed a way of controlling an 80 with a 60 tune, but since my wiring was already set up for an 80 including the addition of the ISS wires, I was just as well off to run the 80 tune segment swap. I think (don't quote me on this) that one advantage to the Slow67 method is that he can control the TC unlocking below 5% throttle as this seems to be something people desire. I just wanted a truck that uses all its gears both on its own and when I tell it to up/down shift!




Next up... DOOR PINS!

Also, aluminum toolbox, maybe a spray in boxliner, DVD headunit, etc.

It is ready for its working life as a daily driver, tow/haul slut.