Electronic speedo hook up problem
09-13-2015, 02:24 PM
#1
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Electronic speedo hook up problem 72 Vette that I have swapped in an 09 LS3 from a Vette. I am running a T56 from an 06 GTO. Aftermarket Autometer electronic speedo and tach. I ran the T56 with this speedo before the LS swap and ran the wire directly to the speedo and it worked fine. After swapping in the LS with a PSI harness I can't get the speedo to work. Every once in a while while driving around the streets I get a little blip of the needle moving. I have hooked up the OBD scanner and the computer is getting a good signal and I can see the speed on the OBD scanner just fine. Is there a setting or filter I need for the wire coming from the ECM to the speedo head?
09-15-2015, 10:12 AM
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That worked for the tach and I had to put a resistor in the line. The spedo does not have a 4 cyl mode. It requires a 5 volt square sign wave. Not sure if the signal from the ecm is this or not.
09-15-2015, 07:03 PM
#4
Ah, I was thinking tach, not speedo on the 4 cyl setting. All the swaps I have done in the past used the 411 ecm, and worked fine wired direct. I am currently working on my first E38 ecm. I wired that direct as well, but the car hasnt been started yet (no inj pulse) I'm not sure if the ecm speedo signals are the same. I hope to have the car started very soon and see if speedo works. Scott
09-16-2015, 04:33 PM
#7
My harness wasn't "hacked" at all. Cut, crimp, solder, heat shrink every connection. Probably better than some of the factory connections I have seen.
And there should be no issue with interference. I'm running t a Cable-X box and ECM and everything works fine.
And there should be no issue with interference. I'm running t a Cable-X box and ECM and everything works fine.
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09-16-2015, 04:43 PM
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I can certainly splice in but is the ECM output the same signal that is going to it from the VSS off the trans. I just thought that they give you a wire for the speedo so it should work. Just curious if the signal from the ECM is the same as the VSS
09-16-2015, 04:50 PM
#9
Thats exactly my point. Splicing into the harness when there is a speedo output makes no sense. I have used the output signal on no less than 10 cars. I just havent used the e38 yet. I should know shortly if its the same, but all I have read says it is.
Scott
Scott