speedometer

[sy2592]

Been looking at posts for speedometer problems and I think I'm more confused than ever.
I've got an LS3 with a 4l80e and the speedometer doesn't start to work until I'm probably doing 25 or 30 mph.....then of course the trans won't shift. Using a Current Performance harness that connects the VSS to the transmission. Should the VSS signal come from the transmission or transfer case? Does the DRAC have to be modified or calibrated?
Any help here would be appreciated ......I'm lost....

 

[sy2592]

Re: speedometer

Been looking at posts for speedometer problems and I think I'm more confused than ever.
I've got an LS3 with a 4l80e and the speedometer doesn't start to work until I'm probably doing 25 or 30 mph.....then of course the trans won't shift. Using a Current Performance harness that connects the VSS to the transmission. Should the VSS signal come from the transmission or transfer case? Whats wrong here? Does the DRAC have to be modified or calibrated?
Any help here would be appreciated ......I'm lost....

Anyone?

 

[BstedElky]

Re: speedometer

For the VSS, that comes off a speed sensor of diff/axle somewhere. You have to make sure the DRAC is getting the right frequency signal. Jagsthatrun sells adapters for transmissions that put out the requisite frequency. I'll look at my books tonight. I know only a little about this because I'm using my El Camino with the Sy engine and certain things like cruise and that don't work yet.

 

[sy2592]

Re: speedometer

Unfortunately I didn't wire it ...but its a Current performance harness...(supposedly made for this application) and there is no connector for the t-case..... only the transmission. Stock DRAC is connected.
Its apparently getting some signal....since the speedometer starts to function at some point.
Some have told me its in the tune but I'm not sure....

 

[sy2592]

Re: speedometer

Tried disconnecting DRAC ...still wont shift

 

[Norm]

Re: speedometer

When you ordered your Current Performance harness, did you tell them it is for a 4x4? You need both signals one in the front of the transfer case ( from the transmission) and the other from the signal on the transfer case. Make sure you also tell them it is from a first gen Sonoma as there are changes from the first series to the second series.

 

[sy2592]

Re: speedometer

When you ordered your Current Performance harness, did you tell them it is for a 4x4? You need both signals one in the front of the transfer case ( from the transmission) and the other from the signal on the transfer case. Make sure you also tell them it is from a first gen Sonoma as there are changes from the first series to the second series.

Interesting....I spoke to Current and was told I only need one connection....They are in the process of sending me a pigtail/adaptor to relocate the trans connection to the transfer case.
I have my doubts.....
If both connections are necessary where would they tie in?? Do they connect right to the DRAC....or the DRAC and speedometer?
Thanks for the help...

 

[Norm]

Re: speedometer

I had two on mine with the BP harness. One was on the transfer case and the other was on the transmission.

 

[68steiny]

Re: speedometer

I built an existing 5.3 truck harness and am also quite confused by the VSS signal, so I won't be permanently wiring it in until it works. I am doing a 5.3/4l60e combo and the 4l60e has a VSS signal on it also...that is why I am waiting. According to the Sy diagrams the VSS goes to the DRAC and probably just provides a speedo signal.

 

[Rice Eater]

Re: speedometer

Was this issue resolved? If it was, can you please share. I am starting to plan my wiring and this is on my list.

 

[anryo]

Re: speedometer

Just for the information, DRAC on our trucks is 4000ppm, but for some strange reason I needed to adjust my Dakota Digital dash for 2440ppm to get correct speedo readings.

 

[sy2592]

Re: speedometer

Was this issue resolved? If it was, can you please share. I am starting to plan my wiring and this is on my list.

Got the pigtail from Current and connected to the transfer case.....no difference.
Unfortunately I had some health problems soon after that and the truck has been siting for almost a year now.
Hope some one here has some success and will share .....want to get back at it soon.

 

[Rice Eater]

Re: speedometer

Got the pigtail from Current and connected to the transfer case.....no difference.
Unfortunately I had some health problems soon after that and the truck has been siting for almost a year now.
Hope some one here has some success and will share .....want to get back at it soon.

Sorry to hear about your health issues, if I figure it out I will let you know.

 

[Syclone#2960]

Re: speedometer

Im glad I found this post...Im having the same "no shift" issue. Unfortunately Im too busy with family/work to mess with.

 

[Jay92Ty]

I know, its a 6 year old post coming back to life, but was just wondering if this (VSS/speedo) ever got figured out?

 

[DaveP's Ghost]

If I were doing one of these conversions, here's how I would do it:

4L60e: Use the T-case sender as an input to the DRAC. Use the 2X output of the DRAC for the trans signal to the transmission controller. (This is exactly how it is done on a 1993/4 S-series 4X4 with the 4L60e.)

4L80e with aftermarket engine management controls: Use the TOSS sender on the transmission for input to the ECM for transmission and other calculations requiring road speed. Use the T-case sender to the existing DRAC for the speedometer. The speedometer won't know the difference, and won't have its calibration affected.