TT Paul Posted February 25, 2017 Share Posted February 25, 2017 Done some google not much use. My speedo is around 10mph out tried moving the needle to set it up with sat nav but to no joy. I'm thinking I need a manual speedo or is there a mod I can do. Been trying to set it up over a month now so any ideas please. Quote Link to comment Share on other sites More sharing options...
LOGIE Posted February 25, 2017 Share Posted February 25, 2017 Correct speedo (manual) would be my guess mate. They are calibrated to run with sensor in gearbox. Are you running any ridiculous wheel and tyre sizes? This can throw speeds out. Quote Link to comment Share on other sites More sharing options...
TT Paul Posted February 25, 2017 Author Share Posted February 25, 2017 Hi chap thanks for input forgot bout wheel size. Just 19 wheels but was OK before 6 speed was just slightly out. Quote Link to comment Share on other sites More sharing options...
Mika Posted February 25, 2017 Share Posted February 25, 2017 (edited) Which diff you got? If you have the Euro/UK/Jdm 6-speed diff, your speedo readout would be correct. If not, maybe one of these would do the trick: http://www.supraforums.com/forum/showthread.php?671481-Installing-a-Yellowbox-V4-speedo-corrector-in-a-Supra-MKIV-SC Here is the straight link for the Yellow box: http://www.yellr.com/index.htm Hope this helps! Edited February 25, 2017 by Mika (see edit history) Quote Link to comment Share on other sites More sharing options...
haz182 Posted February 25, 2017 Share Posted February 25, 2017 I had this, I was still running the auto diff.. fitted a big case from a manual and speedo was correct again. Quote Link to comment Share on other sites More sharing options...
TT Paul Posted February 25, 2017 Author Share Posted February 25, 2017 Ye I'm also running auto diff that's the problem. The yellow box is a good idea though Quote Link to comment Share on other sites More sharing options...
Frank Bullitt Posted February 25, 2017 Share Posted February 25, 2017 (edited) It's not the diff that is the problem, it's the ring & pinion. Is it a large or small case you are running? Edited February 25, 2017 by Frank Bullitt Spelling. (see edit history) Quote Link to comment Share on other sites More sharing options...
Mika Posted February 26, 2017 Share Posted February 26, 2017 ^ Yes, it is the differential ratio which causes the difference in speedo readout. The gearbox speed sensor ratio does not match the differential ratio. The yellow box would be the simplest plug and play solution for this. Quote Link to comment Share on other sites More sharing options...
Burna Posted February 26, 2017 Share Posted February 26, 2017 Ye I'm also running auto diff that's the problem. The yellow box is a good idea though Just check the yellow box will work mate, as I was reading through the website and noticed in the diagrams it shows it converting a square wave speed signal. I'm pretty sure the speed signal into the Supra speedo is a sine wave, then the speedo converts it to a 4 pulse square wave, which then goes to the ECU. It may not matter, but best to check. Quote Link to comment Share on other sites More sharing options...
TT Paul Posted February 26, 2017 Author Share Posted February 26, 2017 Just check the yellow box will work mate, as I was reading through the website and noticed in the diagrams it shows it converting a square wave speed signal. I'm pretty sure the speed signal into the Supra speedo is a sine wave, then the speedo converts it to a 4 pulse square wave, which then goes to the ECU. It may not matter, but best to check. Always something else to check. So a manual speedo won't work then due to ratios being different looks like the yellow box maybe the option as long as it will work. Quote Link to comment Share on other sites More sharing options...
DodgyRog Posted February 26, 2017 Share Posted February 26, 2017 It's the Auto Diff Ratio's that cause the miss read Paul, I have the same problem with a Manual Speedo Cluster Let me know if you try the Yellow Box and it works, as I am not overly bothered by it, but if it's a simple plug and play, I might as well just do it Quote Link to comment Share on other sites More sharing options...
Burna Posted February 26, 2017 Share Posted February 26, 2017 Always something else to check. So a manual speedo won't work then due to ratios being different looks like the yellow box maybe the option as long as it will work. It's worth a punt to see if it works. Quote Link to comment Share on other sites More sharing options...
TT Paul Posted February 26, 2017 Author Share Posted February 26, 2017 It's the Auto Diff Ratio's that cause the miss read Paul, I have the same problem with a Manual Speedo Cluster Let me know if you try the Yellow Box and it works, as I am not overly bothered by it, but if it's a simple plug and play, I might as well just do it Cool thanks rog saves me buying manual clocks will get a box when I find a job lol. There's a V3 box on eBay but says it's for bikes might get one on a punt Quote Link to comment Share on other sites More sharing options...
Hitbox Junkie Posted February 26, 2017 Share Posted February 26, 2017 (edited) At the moment I think I've the same problem. Though I need to play with the needles as they don't seem to work correctly. It read's 10ish mph over. My gears seem short so think I have a UK spec large auto case diff. And the temp gauge reads slightly over too. Let us know how the yellow box goes. Edited February 26, 2017 by Hitbox Junkie (see edit history) Quote Link to comment Share on other sites More sharing options...
TT Paul Posted February 26, 2017 Author Share Posted February 26, 2017 At the moment I think I've the same problem. Though I need to play with the needles as they don't seem to work correctly. It read's 10ish mph over. My gears seem short so think I have a UK spec large case diff. And the temp gauge reads slightly over too. Let us know how the yellow box goes. Glad I asked now not the only one it seems. Quote Link to comment Share on other sites More sharing options...
Hitbox Junkie Posted March 7, 2017 Share Posted March 7, 2017 Ant update on this Paul? Quote Link to comment Share on other sites More sharing options...
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