4l80 swap help...no speedo
Thread Starter
On The Tree
Joined: Feb 2013
Posts: 183
Likes: 7
4l80 swap help...no speedo So,
I've done a 4l80 swap in my ECSB 2006 Sierra, 2wd. It's a late model trans with the front and rear speed sensors separate (one at the front, one at the rear).
It is my understanding that the rear sensor is equivalent to the sensor on the 60e.
The front sensor is the one that needs to be pinned into the PCM.
With that being said,
I've checked and rechecked my PCM connections. I'm using a PNP harness for pre-2007 4l80s.
Segment swap was done. Do these not work sometimes?
My speedometer doesn't work. Additionally, there isn't any speedo feedback in the scanner either. So that tells me the signal isn't making it from the trans to the PCM.
With all that being said, I plan on changing both sensors this afternoon. I mean, what can it hurt, right?
Additionally, could I use a same year van tune file (licensed of course) that supports the 4l80 by default? Assuming I do a VIN change and copy my engine parameters over. Would it work?
I've found a donor file and both are p59 controllers and DBW.
Thanks in advance,
I've done a 4l80 swap in my ECSB 2006 Sierra, 2wd. It's a late model trans with the front and rear speed sensors separate (one at the front, one at the rear).
It is my understanding that the rear sensor is equivalent to the sensor on the 60e.
The front sensor is the one that needs to be pinned into the PCM.
With that being said,
I've checked and rechecked my PCM connections. I'm using a PNP harness for pre-2007 4l80s.
Segment swap was done. Do these not work sometimes?
My speedometer doesn't work. Additionally, there isn't any speedo feedback in the scanner either. So that tells me the signal isn't making it from the trans to the PCM.
With all that being said, I plan on changing both sensors this afternoon. I mean, what can it hurt, right?
Additionally, could I use a same year van tune file (licensed of course) that supports the 4l80 by default? Assuming I do a VIN change and copy my engine parameters over. Would it work?
I've found a donor file and both are p59 controllers and DBW.
Thanks in advance,
Thread Starter
On The Tree
Joined: Feb 2013
Posts: 183
Likes: 7
Thanks.
Changed the rear sensor. No change.
Removed the PNP harness and repinned the connector. No change.
Also verified there was a reluctor ring on the 80e.
Also verified the factory trans connector pinout.
Anyone else?
Changed the rear sensor. No change.
Removed the PNP harness and repinned the connector. No change.
Also verified there was a reluctor ring on the 80e.
Also verified the factory trans connector pinout.
Anyone else?
Last edited by madmann26; Jan 7, 2018 at 01:31 PM.
Thread Starter
On The Tree
Joined: Feb 2013
Posts: 183
Likes: 7
(Assuming you're talking about the rear most sensor)
TECH Fanatic
Joined: Jan 2015
Posts: 1,114
Likes: 33
From: Fort Worth, Texas
OSS stands for Output Speed Sensor, Which is the rear most speed sensor.
It may be easiest to just prove out a few things.....
1. Start engine, With the trans in Park.
2. Find the ISS "PID" on your scanner, It should reading a few hundred RPM in park.
(You can "sanity" check the reading by putting the trans in drive...The ISS RPM will drop to zero)
3. Swap the ISS Circuits into the OSS Cavities, Remove the wires from cavities 22 & 23 (ISS) & install them in cavities 20 & 21. (Green/C2 connector)
4. Start engine/Trans in park......Does the OSS/VSS now have a reading?
This feeds a "known good" speed signal to the OSS input at the PCM. If it now gets a reading......You most likely have a wiring/connection issue.
If not.....PCM issues!
It may be easiest to just prove out a few things.....
1. Start engine, With the trans in Park.
2. Find the ISS "PID" on your scanner, It should reading a few hundred RPM in park.
(You can "sanity" check the reading by putting the trans in drive...The ISS RPM will drop to zero)
3. Swap the ISS Circuits into the OSS Cavities, Remove the wires from cavities 22 & 23 (ISS) & install them in cavities 20 & 21. (Green/C2 connector)
4. Start engine/Trans in park......Does the OSS/VSS now have a reading?
This feeds a "known good" speed signal to the OSS input at the PCM. If it now gets a reading......You most likely have a wiring/connection issue.
If not.....PCM issues!
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Here's another way to test for a faulty VSS (OSS in this case). You will need a multi meter.
Set your multi meter to A/C. Unplug connector on OSS/VSS so that you can see the pins inside the OSS/VSS. With the trans in neutral (engine off) hold each lead of your multi meter to each of the pins on the speed sensor. Now have someone turn the drive shaft (yes, the rear wheels need to be off the ground for this).. While they are turning the driveshaft you should see an A/C signal on the multi-meter. This will prove that the speed sensor is functional so that you are not wasting money on a sensor only to figure out later that the wiring, or PCM, is at fault. Since the speed sensors on the 80E are the same (front or rear), you can try swapping their positions and then check for a speedometer reading after that.
I've seen it before where someone swapped over a 4x4 trans to 2 wheel drive and did not realize that there is NO RELUCTOR ring inside the 4x4 trans as it gets the VSS/OSS from the T-case.. If your trans was converted over from 4x4, put your finger into the rear speed sensor hole and feel for the presence of a reluctor ring. Without it, the sensor will never read/report a signal. It's rare to have problems with speed sensors themselves. It's common to have problems with wiring in the on-body-harness connector as people will pull on the wires to unplug the connector and this can pull the wiring loose from inside the connector, or otherwise damage the wiring where it attaches to the pins in the connector.
Set your multi meter to A/C. Unplug connector on OSS/VSS so that you can see the pins inside the OSS/VSS. With the trans in neutral (engine off) hold each lead of your multi meter to each of the pins on the speed sensor. Now have someone turn the drive shaft (yes, the rear wheels need to be off the ground for this).. While they are turning the driveshaft you should see an A/C signal on the multi-meter. This will prove that the speed sensor is functional so that you are not wasting money on a sensor only to figure out later that the wiring, or PCM, is at fault. Since the speed sensors on the 80E are the same (front or rear), you can try swapping their positions and then check for a speedometer reading after that.
I've seen it before where someone swapped over a 4x4 trans to 2 wheel drive and did not realize that there is NO RELUCTOR ring inside the 4x4 trans as it gets the VSS/OSS from the T-case.. If your trans was converted over from 4x4, put your finger into the rear speed sensor hole and feel for the presence of a reluctor ring. Without it, the sensor will never read/report a signal. It's rare to have problems with speed sensors themselves. It's common to have problems with wiring in the on-body-harness connector as people will pull on the wires to unplug the connector and this can pull the wiring loose from inside the connector, or otherwise damage the wiring where it attaches to the pins in the connector.
Registered User
Joined: Jan 2018
Posts: 2
Likes: 0
So,
I've done a 4l80 swap in my ECSB 2006 Sierra, 2wd. It's a late model trans with the front and rear speed sensors separate (one at the front, one at the rear).
It is my understanding that the rear sensor is equivalent to the sensor on the 60e.
The front sensor is the one that needs to be pinned into the PCM.
With that being said,
I've checked and rechecked my PCM connections. I'm using a PNP harness for pre-2007 4l80s.
Segment swap was done. Do these not work sometimes?
My speedometer doesn't work. Additionally, there isn't any speedo feedback in the scanner either. So that tells me the signal isn't making it from the trans to the PCM.
With all that being said, I plan on changing both sensors this afternoon. I mean, what can it hurt, right?
Additionally, could I use a same year van tune file (licensed of course) that supports the 4l80 by default? Assuming I do a VIN change and copy my engine parameters over. Would it work?
I've found a donor file and both are p59 controllers and DBW.
Thanks in advance,
I've done a 4l80 swap in my ECSB 2006 Sierra, 2wd. It's a late model trans with the front and rear speed sensors separate (one at the front, one at the rear).
It is my understanding that the rear sensor is equivalent to the sensor on the 60e.
The front sensor is the one that needs to be pinned into the PCM.
With that being said,
I've checked and rechecked my PCM connections. I'm using a PNP harness for pre-2007 4l80s.
Segment swap was done. Do these not work sometimes?
My speedometer doesn't work. Additionally, there isn't any speedo feedback in the scanner either. So that tells me the signal isn't making it from the trans to the PCM.
With all that being said, I plan on changing both sensors this afternoon. I mean, what can it hurt, right?
Additionally, could I use a same year van tune file (licensed of course) that supports the 4l80 by default? Assuming I do a VIN change and copy my engine parameters over. Would it work?
I've found a donor file and both are p59 controllers and DBW.
Thanks in advance,
Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
I would start over and redo the segment swap. I've done two this year and both worked flawlessly though I'm using the older PCMs. I found a matching OS from a savanna van.