WS6HUMMER

iTrader: (19)

I didn't do the swap or tune but I'm trying to help because no one can figure this one out. It's an 03 Silverado 1500, it has been segmented properly, the ISS sensor has been connected to pins 22 & 23 of the PCM on the green connector. I've even ohmed the ISS & VSS sensors & they check out ok, they bought the kit from PATC btw. When I scan this truck everything seems ok with the exception of the VSS. It won't shift out of first gear & the scanner reads the MPH but it will drop the reading down really low periodically so I'm sure that has something to do with it but I'm not sure what's making it do that. This is the second 4L80 they put in this truck and they both do the same thing. Its also throwing DTC's P0753 P0758 P1810 P0748, just looking for ideas of what to check next any input is appreciated.

mrvedit

Until the speedo reads accurately I would ignore trans codes.
We've had several threads in the past year concerning stubborn VSS problems. IIRC, one turned out to be a corroded connector and the soultion was to splice in a new pigtail. I seem to recall another one where the wiring appeared to have gotten too close to the exhaust and melted. In an older thread the OP simply replaced the VSS.
Since you confirmed the wiring with an Ohmmeter, I would look carefully at the connector as you seem to have intermittent problems.

BTW - I'm not doubting that pins 22&23 are correct, but for some vehicles I see that the Green connector has the VSS on pins 20 and 21. For 1999-2003 trucks I see that the VSS is on pins 20/21 for 4.8/5.3 engines and pins 22/23 for 6.0 engines. Crazy.

WS6HUMMER

iTrader: (19)

Thanks for the input, really appreciate it. That's pretty interesting about pins 20 & 21 on the green connector wiring harness. Will look into that.

5.0 LsX

iTrader: (7)

had a similar issue with my swap recently, trying to track down drivability issues and codes, tried 3 diff segment swaps and everything else I could check myself. dropped it off with a well known shop/tuner, he saw the vss wasn't reading correctly, ended up being the wrong or something wrong with the segment swaps

5.0 LsX

iTrader: (7)

pin 20 and 21 should be the iss btw

WS6HUMMER

iTrader: (19)

Thanks! I checked the original VCM ID, found another tune with the same ID that came with a 4L80, compared it to the vehicles tune & it had no gray areas indicating that the 4L80 segment was correct. I think this vehicle is pinned wrong, it's pinned on 22&23 as per PATC's instructions but according to you and others it's not.

5.0 LsX

iTrader: (7)

20 21 is the VSS, 22 23 is the ISS . Just double checked my wiring schematic from PSI

WS6HUMMER

iTrader: (19)

Thanks!

slow67

iTrader: (2)

Your post is confusing. ISS = front sensor, VSS = rear sensor.
20 and 21 is the Vehicle Speed Sensor (VSS).

5.0 LsX

iTrader: (7)

edited for you. was going off memory

WS6HUMMER

iTrader: (19)

So what pins do you wire the ISS sensor to since a 4L60 already has a VSS? From my little bit of research you only wire in the ISS when you do a 4L80 swap when converting from a 4L60. PATC says to use pins 22 & 23 of connector #1 which they say is red and if it's not to use the green connector of the PCM.

5.0 LsX

iTrader: (7)

20 21 is the VSS, 22 23 is the ISS
this is correct.

I think you are getting confused with a 4l60 to 4l80 conversion -vs- pinning for a 4l80 and doing a segment swap. Did you get a 4l60->4l80 adapter harness, or a 4l80 universal harness that needs to be pinned to the pcm?

slow67

iTrader: (2)

X2. This is correct.

WS6HUMMER

iTrader: (19)

This is a PATC 4L60 to 4L80 conversion harness, in my original post I also mentioned that the tune has been segmented for a 4L80 as well. PATC's instructions call for you to input the ISS wires into pins 22 & 23 of the red PCM connector which is connector #1. This particular vehichle is an 03 and has a green connector for connector #1 and PATC does mention that some vehichles come with a green connector for connector #1 though.

5.0 LsX

iTrader: (7)

a conversion harness is made to run off of the 4l60 tune, have to swap a couple wires and add a relay, although I have only dealt with the red/blue connectors. you cannot have an adapter harness from a 4l60 harness and control a 4l80, unless PATC is wired differently... there are a few different pinouts and the 2-3 solenoid works in reverse.
I would call PATC to verify

WS6HUMMER

iTrader: (19)

I did, I called PATC more than once actually, their harness plugs in, you run 2 wires for the ISS and do a 4L80 segment swap and you're supposed to be good to go. I told Nathan at PATC what it's doing and the dtc's that I got and he's suspecting a bad wiring harness. IIRC it had a FTP related DTC and he says for it to set that something inside the harness is messed up because whatever sets it is made into the vehicle wiring harness. I'm just not ready to say for sure it's a harness.

5.0 LsX

iTrader: (7)

what does their harness look like? is there a relay and a couple wires that cross pin?

WS6HUMMER

iTrader: (19)

No I don't see any kind of relay, it's just a short harness with plugs on either end. PATC does specify that the 4L80 you use must have a gray valve body plug and it does. If you look on their website you'll see the conversion harness they sell.

5.0 LsX

iTrader: (7)

I cant tell with out looking at the pinout...but heres the pinout I have for a 4l80 w a 4l80 segment swap, this is for red/blue connector, but with the correct segment swap it should be just fine pinned the same on the green connector

a to red 48
b to red 47
c to red 6
d to red 8
e 12v+ on ignition
L to red 51
m to blue 53
n to red 63
p to blue 18
r to blue 17
s to red 2

VSS pin a to red 20
VSS pin b to red 21

ISS pin a to red 22
ISS pin b to red 23

WS6HUMMER

iTrader: (19)

Thanks man, I'll check it out. Either way I'll post up what ends up fixing it for people searching this topic in the future.