Mo Reviews Posted January 27, 2020 Share Posted January 27, 2020 We're looking for a copy of the wiring diagram for the Tiptronic speedo/instrument cluster. Following the installation of a standalone Syvecs S6+, the speedo is no longer getting a speed pulse from the gearbox via the ECU so we're not getting a reading on the speedometer. Interestingly, all the other gauges appear to be unaffected, including the odometer. We're therefore looking to find a work around to get the speed pulse to the instrument cluster without having to reinstall the stock ECU and piggy backing the standalone... Many thanks in advance. Quote Link to comment Share on other sites More sharing options...
Mike2JZ Posted January 27, 2020 Share Posted January 27, 2020 The speed signal of the gearbox goes directly to the Speedo cluster via 36pin orange plug in passenger footwell, afterwhich that signal is then distributed to the ODO, ECU & PPS. Most Syvecs plug and play harnesses I've seen do not intercept this signal in any way, so there will be no difference between running syvecs or stock ecu. Obviously if someone has changed this to run the speed signal through ECU first then anything could be possible. Assuming your ODO works and ECU is receiving a speedo signal from the output of the combination meter then this will narrow down your speedo issue to: a) Faulty combination meter PCB b) Faulty speedo gauge c) Faulty KPH to MPH converter wiring d) Faulty wiring on plugs behind combation meter Quote Link to comment Share on other sites More sharing options...
Mo Reviews Posted January 27, 2020 Author Share Posted January 27, 2020 (edited) Thanks Mike, this may end up being something you'll need to breathe on soon if I can't get to the bottom of it... You mention the ECU getting a feed from the speedo signal, my ECU seems to get the pulse from the ABS sensor... is that what you would expect? Edited January 27, 2020 by Mo Reviews (see edit history) Quote Link to comment Share on other sites More sharing options...
Mo Reviews Posted January 27, 2020 Author Share Posted January 27, 2020 Repost. Please see above. Quote Link to comment Share on other sites More sharing options...
Mike2JZ Posted January 27, 2020 Share Posted January 27, 2020 Thanks Mike, this may end up being something you'll need to breathe on soon if I can't get to the bottom of it... You mention the ECU getting a feed from the speedo signal, my ECU seems to get the pulse from the ABS sensor... is that what you would expect? On the typical plug & play harness for syvecs, it uses the speedo signal from dash. However, it's totally acceptable and do-able to use an ABS speed signal. If your car has been setup to use traction control it will need to use a minimum of 1 front 1 rear sensor plumbed into the syvecs. Once done, in addition to TC you can allocate one of these sensors for what the ECU determines as the 'Vehicle Speed'. The question will be, does the ECU then output this speed signal to the Dash. Or is the dash still connected directly to gearbox? An easy way to determine this is to go into your Syvecs I/O configuration and see if 'Trip Meter' has been allocated on one of your outputs. Quote Link to comment Share on other sites More sharing options...
Mo Reviews Posted January 27, 2020 Author Share Posted January 27, 2020 On the typical plug & play harness for syvecs, it uses the speedo signal from dash. However, it's totally acceptable and do-able to use an ABS speed signal. If your car has been setup to use traction control it will need to use a minimum of 1 front 1 rear sensor plumbed into the syvecs. Once done, in addition to TC you can allocate one of these sensors for what the ECU determines as the 'Vehicle Speed'. The question will be, does the ECU then output this speed signal to the Dash. Or is the dash still connected directly to gearbox? An easy way to determine this is to go into your Syvecs I/O configuration and see if 'Trip Meter' has been allocated on one of your outputs. The car is indeed set up to make use of the Syvecs TC feature so that must be the case with the ABS sensors. I'll have a look at the gearbox speed pulse wiring and the Syvecs I/O configuration tomorrow and report back with my findings. Thanks again Mike. Quote Link to comment Share on other sites More sharing options...
Mo Reviews Posted January 28, 2020 Author Share Posted January 28, 2020 (edited) Right, for one reason or another, when testing the connector at the back of the instrument cluster, there was absolutely no speed signal coming from the corresponding wires on the orange 36 pin connector in the passenger footwell. Which itself was getting a speed signal from the gearbox. Clearly therefore, there was an issue in the loom going from the connector in the passenger footwell to the connector in the back of the instrument cluster. So, we ripped it all out, put a new loom in and lo and behold, we got a speed pulse at the back of the instrument connector, plugged it in and I am very pleased to report that it now works perfectly! A very big thank you to Mike for his pearls of wisdom, as usual. Here is a link to the wiring diagram we were able to find which was also quite helpful in our diagnostics: http://www.2jzgarage.com/wp-content/uploads/2012/01/Body_Loom_Connectors.pdf Edited January 28, 2020 by Mo Reviews (see edit history) Quote Link to comment Share on other sites More sharing options...
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