LSx swap Speedo ?

[Clyde65]

I have the 4.8/4l60e in my truck along with a Dolphin electronic speedo, when I am just driving, the speedo looks pretty acurate, however when I slow down and stop the speedo goes all the way to max speed and when I am stopped hovers around 60mph or so, any ideas?

I was told by Dolphin to hook the wire from the trans straight to the speedo to see if this works, how is everyone else hooking their electronic speedo up? I have a stock modified harness( by W4M) and they provided a stub out wire for the speedo, which is what the speedo's wire is connected to. Any assistance would be great.

[BR3W CITY]

Hmm, im doing my swap as well and havn't come on this yet. The wire off the harness would probably be AFTER the pcm right? Im guessing the gauge wants the signal right off of the trans. Not 100% but it makes sense in my head.

[Clyde65]

I asked the guy that did my harness and he said it should go through the pcm, the guage people say straight from the trans, idk.

[Shon]

any other gauges acting funny? could it be a grounding issue?

[Clyde65]

everything is working fine, I thouht about the ground, so I regrounded it. I am really at a loss.

[Shon]

Electrical interference!?!?
is dolphin willing to test the speedo to rule out that its messed up?

[Clyde65]

IDK, I havent asked them, I would have thought for good customer service they would offer, but they havent, just a bunch of check this and check that. I really hate this cuz now I wish I would have spent the extra and went with an Autometer or something like that. It seems these Dolphins do not read quite right wither. For instance, my Dolphin volt meeter reads 14.5+ volts when driving down the road without any accessories on, is that weird?

[Shon]

dont know if that is weird or not but my CTSV shows 14.5 nearly all the time....
have not really looked at my truck logs to see what the volts say.....

[Clyde65]

I have had these guages for quite some time and they hadnt given me any issue, now, with this.

[Shon]

What has changed from then to now???

[Clyde65]

The LS install.

[raycow]

Were you driving the speedo directly from the transmission before the LS install?

Ray

[Clyde65]

No actually before the LS, I had a mechanical speedo. this one has really never worked properly. I had my mechanic friend hook up his diagnostic computer to the ODBII port while I was driving the truck, it Definately is the speedo, so I have sent it off to see if they will fix and/or charge me for repairs. We will see.

[menace121978]

subscribing... i'm hooking up my autometer speedo now but i was looking over the wiring diagram for it and it says there is supposed to be 2 wires for signal input. 1 from the computer and one from the tranny. i'm stumped because i only have 1 wire. and its coming from the computer. any input on this?

[MrDude_1]

Its because the PCM puts out a 5v square wave signal.
your aftermarket speedo is looking for a slightly higher sinewave signal.

the guy with the harness and PCM tuning ability would always want you to use the PCM wire, because it give him full power to change the output to the speedometer. he can tune it for gears, and he knows the PCM is getting the proper VSS signal.. this is important for some small things, like fans.


since its aftermarket, and can be "programmed", the gauge company will suggest connecting it directly to the VSS. they arnt used to talking to people that can program their PCM output signal, and have provided their own calibration method.

options:
1. you can build a small simple circuit to round off the square wave.. you might also want to do a 'pull up' circuit at the same time to raise it from 5v to 12. this would be my solution.. but im also another guy that can use/program the PCM.

2. SPLICE (not cut) so that the VSS signal goes to both the PCM AND the speedo... this is the easiest option.

[Clyde65]

so just splice into the wire from the transmission to the PCM and hook it up to the speedo? Will this make so there will be little or no programing on the speedo? Why doesnt everyone had this issue with ALL the swaps?

[mrhino]

what Mr. Dude said:
1. you can build a small simple circuit to round off the square wave.. you might also want to do a 'pull up' circuit at the same time to raise it from 5v to 12. this would be my solution.. but im also another guy that can use/program the PCM.


your PCM supplies the speedo pulse. do a google search on, how to make a pull up circuit. less than $10 or you can buy one from autometer or dakota digital one for about $80. I have classic instrument gauges and im about a week away from doing the same thing.

[boostat4500]

I have Dolphin gauges in my Burb. Connect to the VSS signal coming out of the PCM and do your calibration drive. You should be fine then.

[Clyde65]

That is exactly what I did, I sent the speedometer back to Dolphin to see if there is a problem, if it doesnt work when I get it back, I will change guages.

[tonypaul]

You might need ine of these:
http://www.summitracing.com/parts/ATM-5291/

or this :
http://cgi.ebay.com/ebaymotors/ws/eB...category=33678

Sure would be nice if these would work with our factory speedos.....

[Clyde65]

tonypaul,

I have a 4l60e trans so it only has a wire, no cable on it. So It doesnt look like these will work. Thanks though!

[tonypaul]

Im sorry- I dont know what I was thinking.....well I do... Im currently trying to decide what speedometer I going to use with my 7.4l/4l80e swap and I just had my stock speedo in mind.... I just didnt have your setup in my head, Im just getting too old..... Hope everything ends up working for you!

[Clyde65]

No problem at all, I am in the same boat, I had to read it at least 3 times before I realized, I also looked at your links and though...hmmm maybe, then read more. So dont worry about it, we all get our minds wrapped around one thought and mix it with something else. I finally got the speedo to Dolphin for them to check it out and fix it, waiting to hear what the plan/status is. Thanks for you help and wishes.

[60apache]

clyde I have been doing research for my ls1 swap that I am in the middle of so I will know how to hook up my dolphin gauges. did you ever fix your problem or come up with a solution?

[Clyde65]

I did, you have to hook it up at the VSS out wire by the trans and THEN calibrate it. Dont let anyone tell you to hook it up out of the PCM, it wont work properly.