Where to fit Truspeed speedo calibrator?

[davidsonsm]

Am I correct in fitting a speed calibration device by cutting into the yellow and green wire that comes from the abs ecu (connector C116L, wire 28) and enters the BeCM at connector number C114 (wire 11)? I plan on making the tap in under the seat so the device is handy (it has two settings for different sizes tyres).

I'm thinking that's the best place so the speed input to the BeCM is corrected prior to it using it for outputs to the speedo etc. That way the speed sensitive interlocks are adjusted too (e.g. the airbags).

How many of you guys have bothered with the correction whilst running bigger tyres. Wanna get the computer accurate again. The 803mm tyres are 8% bigger and funnily enough that's what the speedo is out when compared against GPS.

Through this process I've discovered that I can download an app called ulysse speedometer that has a head up display function. Cool. Gonna try that also, but think I need some reflective tape on the windscreen.

[Keithy P38]

Ill be watching for the answer too (33's very soon)!

Cheers
Keithy

[mtb_gary]

Ill be watching for the answer too (33's very soon)!

Cheers
Keithy

Me too! My road wheel and tyre is fine but the 33 muddies are way out for the calibration.

Gary

[FANTOM P38]

Dont have any answer for you Sean but will watch with interest as my speedo is out due to the 33's, I know to allow for this when i;m driving but worry if the missus jumps in and gets caught speeding unintentionally! Hope you can get it sorted and update us all as to how you did it. (pics) etc.

[mtb_gary]

Dont have any answer for you Sean but will watch with interest as my speedo is out due to the 33's, I know to allow for this when i;m driving but worry if the missus jumps in and gets caught speeding unintentionally! Hope you can get it sorted and update us all as to how you did it. (pics) etc.

Current solution is a dash mounted GPS with speed display
Gary

[davidsonsm]

Think I'm on the right track. Just waiting for truspeed to be delivered. And reckon the positive feed to the device should work with the ignition position 2 & 3 power supply which I believe is wire no.15 on the same connector. That's easy enough to test. But testing the yellow and green wire that receives a pulsed signal from the abs ecu - could that be done with volt meter set to ac current?

[FANTOM P38]

Thanks Gary, Have GPS built into head unit but dont think the missus would know how to use it :wasntme:

I use it myself but would be far simpler if dash /computer was accurate.

[mtb_gary]

Thanks Gary, Have GPS built into head unit but dont think the missus would know how to use it :wasntme:


It was a tongue in cheek comment re GPS, but I can relate totally to your comment re who uses the GPS for speed :D

Gary

[Hoges]

All this talk of speedo calibration etc reminds me of a comment I once read about a bloke who in the 60s drove a Jaguar 3.4 :D: His elderly mother constantly criticised him for speeding so when he found he had to drive her from Melbourne to Sydney he swapped the positions of the speedo and tacho. Result: his mother happily told her friends that her fears were misplaced and he was a careful driver because: "he stayed between 40 and 50 for most of the trip":eek: :wasntme:

[Hoges]

Ill be watching for the answer too (33's very soon)!

Cheers
Keithy

what brand of "shoes" does it wear at present?

[Keithy P38]

255/70 KM2's

[mtb_gary]

davidsonsm

It looks like you've got a few (big) p38 projects on the go at present! Since your Truspeed post I've done some searching around on these devices, they certainly get a good rap from those who have them. Did you source yours locally or on line, and which model do you have? Also interested if you finished up testing the location of where to install the unit and where to cut it into the wiring.

Gary

[davidsonsm]

Found it on eBay out of the states. 2nd hand but unused. Model is 33002. Still awaiting delivery.

Yeah. Seem to be spinning quite a few p38 plates at present. All good fun, but I'll be glad to draw a line under it soon.

[mtb_gary]

Am I correct in fitting a speed calibration device by cutting into the yellow and green wire that comes from the abs ecu (connector C116L, wire 28) and enters the BeCM at connector number C114 (wire 11)? I plan on making the tap in under the seat so the device is handy (it has two settings for different sizes tyres).

I'm thinking that's the best place so the speed input to the BeCM is corrected prior to it using it for outputs to the speedo etc. That way the speed sensitive interlocks are adjusted too (e.g. the airbags).

How many of you guys have bothered with the correction whilst running bigger tyres. Wanna get the computer accurate again. The 803mm tyres are 8% bigger and funnily enough that's what the speedo is out when compared against GPS.

Through this process I've discovered that I can download an app called ulysse speedometer that has a head up display function. Cool. Gonna try that also, but think I need some reflective tape on the windscreen.

Did you ever get around to fitting the Truspeed? I notice back in Dec 2004 Andrew Parker (rangerovers.net) did the same thing as you are suggesting

"If you have a P38A RR or a DII and have put larger tires on the rims, you might be interested in this device for getting your speedometer and other electronic portions of your drive train back in sync. This blurb is a year or two old. I put one of these in between the ABS micro processor and the BeCM on my P38A some time ago now. It sits on the top of the BeCM quite niecely and the wires are easy to get at and splice into for the proper connection. I am currently running 265/75R16 BFG AT's".

Gary

[davidsonsm]

I'm afraid I haven't had time yet. It's been delivered. But reckon I'm on the right track with what I've described.

I'm heading overseas for two weeks as of this Sat, so it'll be early October before I get around to it. In theory, it shouldn't take too long.

[mtb_gary]

Enjoy the holiday

Gary

[davidsonsm]

I just noticed that JayCar have the Mark II version of their speedo calibration device available. They sold out of the Mark I kit. The Mark II kit comes pre-soldered. It needs wires and a box.

Speedo Corrector MkII Kit - Jaycar Electronics (http://www.jaycar.com.au/productView.asp?ID=KC5435)

I'm still planning on fitting the TruSpeed device - given I've bought it. Not forgot about it, just been overseas and busy with the non-LR aspects of my life. These aspects do exist.

Hopefully this weekend, I'll find some time to fit it. The bloody snorkel has been devouring all my spare time.

[davidsonsm]

I fitted the truspeed. It appears to work like a dream. It has two switch positions for differing wheel diameters and each quarter turn represents a 1% speed increment. It appears to be bang on after driving down the road comparing against gps. Happy bunny. It is the yellow and green wire in position no. 11 on connector 114 that I've tapped in to. The other two wires are live and earth.

[mtb_gary]

I fitted the truspeed. It appears to work like a dream. It has two switch positions for differing wheel diameters and each quarter turn represents a 1% speed increment. It appears to be bang on after driving down the road comparing against gps. Happy bunny. It is the yellow and green wire in position no. 11 on connector 114 that I've tapped in to. The other two wires are live and earth.

Well done, I'm still waiting for one to turn up on ebay ;)

Gary

[FANTOM P38]

Well done Sean sounds like another job down the track as I plan to swap over from Muddies to std roadies from time to time and this beats remembering speedo variances! With potential fines in the offing makes good sense to fit similar thing.