jon_dragon Posted January 18, 2011 Share Posted January 18, 2011 HELP! Im having an issue with my speedo! Im not entirely sure whats wrong with it but its not reading correctly. I thought it was reading in Kph which would suggest the speed converter was faulty but that de limits the car too and I can do over 112 so I shouldnt imagine half its functionality should fail and not the other half. Anyway, I looked at another speedo with Mph and Kph next to eachother and I dont think its reading in either as none of the numbers match up to what my sat nav tells me. So it turns out its just being lazy. When im doing 30Mph my speedo says 20. When im doing 60Mph, speedo says 40. I just dont get it, what could it be?? Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted January 18, 2011 Share Posted January 18, 2011 Is it auto? Quote Link to comment Share on other sites More sharing options...
jon_dragon Posted January 18, 2011 Author Share Posted January 18, 2011 no its a manual. '95 n/a Quote Link to comment Share on other sites More sharing options...
Abz Posted January 18, 2011 Share Posted January 18, 2011 Do you have aftermarket speedo dials on? Quote Link to comment Share on other sites More sharing options...
jon_dragon Posted January 19, 2011 Author Share Posted January 19, 2011 I did have but Ive taken them off. The problem started when I had the engine replaced. Quote Link to comment Share on other sites More sharing options...
Nic Posted January 19, 2011 Share Posted January 19, 2011 The speedo convertor would be the most likely cause of the problem. You say the speedo is under reading (ie. 60mph actual speed - 40mph indicated speedo speed), if that's the case 112mph reading on the speedo would be a lot higher actual speed. Has the car got stock gearbox, diff final drive gearing and correct tyre sizes? Quote Link to comment Share on other sites More sharing options...
stevie_b Posted January 19, 2011 Share Posted January 19, 2011 It's possible that the converter has lost half of its functionality. Some (most?) converters output the speed signal and delimited signal to different parts of the loom, so it's feasible. Quote Link to comment Share on other sites More sharing options...
Mistermann Posted January 19, 2011 Share Posted January 19, 2011 What size wheels do you have on the car? Quote Link to comment Share on other sites More sharing options...
Nic Posted January 19, 2011 Share Posted January 19, 2011 What size wheels do you have on the car? Size of the wheels would make no difference, tyres with the wrong aspect ratio would throw the speedo out. Although if the speedo is 20mph out, I doubt it'll be the tyres. Quote Link to comment Share on other sites More sharing options...
Mistermann Posted January 19, 2011 Share Posted January 19, 2011 Hmmm, it would appear that i have a similar problem then! I've been driving my TT on 19inch wheels and just assumed the difference would be that....i'll keep an eye on this thread from now on then Quote Link to comment Share on other sites More sharing options...
Nic Posted January 19, 2011 Share Posted January 19, 2011 Hmmm, it would appear that i have a similar problem then! I've been driving my TT on 19inch wheels and just assumed the difference would be that....i'll keep an eye on this thread from now on then The standard 17" wheels/tyres have a certain overall diameter (Front - 64.3cm/Rear - 63.5cm). If you fit 19" wheels then you should fit tyres with a smaller tyre wall so that the overall diameter is as close to stock as possible. ie. the wheels may be bigger but the overall diameter of the wheel/tyres stays the same. The wrong size tyres will make a little difference, they'd have to be a long way out to make a 20mph difference. Quote Link to comment Share on other sites More sharing options...
Mistermann Posted January 19, 2011 Share Posted January 19, 2011 thanks Nic, thats useful info...I'm off to measure the diameter of my wheels now Quote Link to comment Share on other sites More sharing options...
Nic Posted January 19, 2011 Share Posted January 19, 2011 Use this TYRE CALCULATOR, put the stock tyre size one side and your tyre size the other and it'll tell you how the diameters/circumference compares. Stock Tyre Sizes Front - 235/45R17 Rear - 255/40R17 Quote Link to comment Share on other sites More sharing options...
Mistermann Posted January 19, 2011 Share Posted January 19, 2011 V.Impressive - Having put my figures in, as you correctly pointed out, there was very little difference in speed! Quote Link to comment Share on other sites More sharing options...
jon_dragon Posted January 19, 2011 Author Share Posted January 19, 2011 (edited) my tyres arent the issue, the gear box and diff are all stock so I think Im gonna order a new speed converter. Seems Thor have,nt made any new ones yet Ill have to get one off flea bay and check over the connections. Edited January 19, 2011 by jon_dragon (see edit history) Quote Link to comment Share on other sites More sharing options...
JohnHandy Posted January 30, 2011 Share Posted January 30, 2011 my tyres arent the issue, the gear box and diff are all stock so I think Im gonna order a new speed converter. Seems Thor have,nt made any new ones yet Ill have to get one off flea bay and check over the connections. Did this work mate?? I have the same problem but all my diff box ect are not standard! Quote Link to comment Share on other sites More sharing options...
jon_dragon Posted February 4, 2011 Author Share Posted February 4, 2011 No. Ive just fitted the new converter but its just as lazy as the old one Im gonna give it to Keron to fix. I think He might have done something when he changed the engine Quote Link to comment Share on other sites More sharing options...
jon_dragon Posted February 4, 2011 Author Share Posted February 4, 2011 Infact, I've just been on a test run and my engine light came on! So this is a note to other users. Don't get the. Heap electronic speed converters off eBay because they don't work with supras! I'm putting the old one back on tomorrow! Quote Link to comment Share on other sites More sharing options...
JohnHandy Posted February 4, 2011 Share Posted February 4, 2011 No. Ive just fitted the new converter but its just as lazy as the old one Im gonna give it to Keron to fix. I think He might have done something when he changed the engine I think mine is because of the diff as its a V161 box and auto LSD, great for acceleration but not good for speedo Keron is a top guy and will look after you no problem. Quote Link to comment Share on other sites More sharing options...
jon_dragon Posted April 11, 2011 Author Share Posted April 11, 2011 Ive just done a bit more research on this after talking with my technical guys at work (toyota) They said test it against a sat nav. If the speedo is wrong then the milage will also be wrong! Ive been on a 5 mile round trip according to the sat nav but my car reads 3 miles. This would indicate that the problem is not with the speed sensor in the gear box but with the dash pod it's self! I can get a brand new electronic part of this for about £45 from work but Id rather just blitz the whole thing and replace the lot... its the only way to be sure! Quote Link to comment Share on other sites More sharing options...
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