NC_Steve

I have just built the Jaycar speedo corrector and fitted it to my car, but it doesn't work like it should. It doesn't seem to adjust the speed at all, but the speedo still works. You can turn the two switches that are supposed to adjust the speedo, but they do nothing. So I am wondering if anyone else has fitted this kit and has it working? How did you connect it to the speedo? I cut the red wire behind the cluster. When I cut it the speedo no longer worked so I am guessing its the right one? Also if anyone has built the kit what did you set the links to? and did you fit R1 or R2? I have fitted R1 and set both links to X.

Appreciate any help

EFFalcon

I beleive santo installed one of these... he might know.

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needturbo6

did you install one because of a diff ratio change? as i think the better way is to cut the wire at the speedo transducer, so the computer will be fooled too, and shift at the right points.

not quite sure about the wire though, could possibly be a power wire, check it with a test light maybe

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EFFalcon

with a diff ratio change... i think u wanna let the speedo know that the change has been made, not the ECU.
i think with the ECU knowing, it throws shift points way out (hitting limiter n stuff)

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dansedgli

Santo never got it to work, which is why he bought my apexi RSM.

needturbo6

I just remembered NC-Steve has a five speed box so it doesnt matter where it gets its input from.....


i dunno if this was directed at me or u got speedo and ecu around the wrong way in the first sentence....

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EFFalcon

was directed at u
the auto has hissie fits with diff chagnes if the ECU knows of the diff change.
even going from 3.08 to 3.45 throws the shift points out if u put the correct speedo gear in.

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needturbo6

thats is pretty much what i said...

the speedo transducer is the bit on the side of the gearbox that sends a signal to both the ecu and the speedometer and if the jaycar is spliced into here then it will correct both problems.

i dunno if my post was hard to translate..? should i go back to school?

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EFFalcon

no.. i'm saying the opposite to u.
if the ECU realises its doing the wrong speed at the wrong RPM (what would happen if put between gearbox and ECU) then it gets confused.
where as if its simply used to correct the Speedo calibration, the ECU still thinks the stock diff is there.

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needturbo6

im confused. ill state my opinion and then go from there...

what im saying is: If there has been a diff ratio change it puts both tranny shift points and speedometer out of whack. by using the jaycar kit inbetween both, the ecu thinks the stock diff is there and the speedometer also thinks the stock diff is there. both problems would then be fixed.

(sorry bout thet thread hacking guys, though its not too far off topic...)

EFFalcon

so basically what you're saying is.
the Jaycar kit will trick both the ECU & Cluster?

What i'm trying to say is, by tricking the ECU & Cluster, the ECU beleives the car should be at (for example) doing 1500rpm @ 90km/h
by tricking both, you're telling the ECU that it is doing 1500rpm @ 75km/h <-- this is wrong thus shift points effected. but speedo is reading correct.

by tricking only the speedo, the ECU still gets the same signals for what speed/RPM it is doing, but only the Speedo is receiving the corrected speedo values.

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needturbo6

yes, if placed after the speedo transducer, and only needed this way if there has been a diff ratio change and is an auto


id say that is correct but only it still used a stock diff ratio and therefore giving an incorrect reading to the ecu.


but only if the car had the stock diff ratio?

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EFFalcon

i'm only talking about a car that is auto. and has a non-standard diff ratio.
i don't know why you would fit a speedo correction unit to a car with a stock diff?

what i'm saying applies to for instance, a 4 speed auto GLi (3.08 stock diff) with a 3.7 diff fitted.

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needturbo6

it is needed to be placed in between otherwise the ecu will get readings that are meant for the stock diff ratio and its higher speed in each gear.

I think its ****n funny how we are not understanding each other at all and totally thread mining. other people will read this tomorrow and think wtf?
I dont know why as i feel im saying what your saying in a way. i think it might just be past my bedtime

back on topic and off topic at the same time.

So what you r trying to say is by leaving the signal to the ecu alone, the shift points will remain the same?

EFFalcon

thats exactly what i'm saying.

the ECU controls shift points by matching speeds with RPM's.
by changing the diff ratio, you change road speed to RPM ratios *ONLY* if u change the speedo gear or use electronics to trick it.
if u leave the stock speedo gear in it and just leave it alone, the car will drive using the correct shift points, but your speedo will be way out (as the car doesn't even realise the diff is changed)

so by leaving this alone, and only telling the cluster to correct readings, as far as the ECU is concerned, there is still a stock diff, but the speedo is now ready correctly.

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needturbo6

ahh, i understand what u are trying to say now.

What im trying to say is that with a different diff ratio the ecu doesnt know, this can cause the shift points to be higher or lower as well. you want the ecu to be fooled into thinkin the stock diff is there, otherwise the reading from the transducer will be different to a stock diff ratio and therefore mess with the ecu's brain. just like this thread is doin :

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EFFalcon

by not changing *anything* the car thinks the stock diff is there.
how would the car know anything has changed if its still getting the same reading from the speedo gear in the transmission.

changing the diff itself will make no difference.

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needturbo6

id have to disagree with that, the ecu uses the speedo transducer to work out shift points, changing the diff ratio will cause the wrong input and the shift point wont be correct, unless possibly the diff ratio change is minor.

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bindi

Damn straight! lmao if I knew what parts you guys were actually talking about (as in, seen them in bits and knew what they did) then this might make sense.

I was curious about this whole thing of the Jaycar speedo gadget. I know my speedo is way out. It used to be that I'd have to do what the speedo said was 70kph to do 60kph. Then we got the newer engine and the 15" rims, and then it was 65kph to do 60kph.

Then the speedo gear died. I did not know you could get different speedo gears for different diffs etc until now!

Another speedo gear was put in at the wrecker, and now it's totally opposite - we have to do 55kph to do 60kph! This has taken a bit of getting used to.

So this Jaycar thing is supposed to work by fixing those issues as outlined above? And by the sounds of it, you have to splice it in somewhere between your ECU and your speedo? So that the ECU doesn't know of the diff change yet the speedo will give you the real speed...

Ok, so my question to the original question asker is - did you ask the blokes at Jaycar how to actually put it in or did you just walk out of there like the average man and think "instructions are for wusses, who needs them"???!!! lol

I am very curious about this cos I am sick to death of trying to keep the Ford to the speed limit around cameras and cops...

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deankdx

alright now we're back on track.
i had soimilar issues with the LEXUS motor and auto in my XF, speedo out and hitting limiter in first,so heres what i know.

i'm not sure where the ford gets its signal from for the auto... the lexus used to get its signal FROM the speedo. this is where my problems arose, as i'm not using the lexus speedo, so had to run the imput straight from the transducer. i was lucky as there are different pulse per rev transducers available and when i got the trans working properly i fluked having the speedo read near perfect. what does this have to do with this thread you ask?
i was almost in agreence with needturbo6 until i thought about the possibility of where the trans gets its signal from, MAYBE it is from the speedo?
on the tranducer there is three wires,(on an XF, i assume they are the same on later models) one is for power one is earth the other is signal, colours may vary.
when i was at my local speedo place geting things calibrated(tacho, temp guage etc) he said i may need an electronic ratio box, at $330 i think fitted, not sure what the JACAR kit costs but it may be not suitable, he also said they could reposition the speedo needle to read accurate, but the odometer would still not be accurate. options are out there, i've probably made no sense at all though

NC_Steve

After a bit of mucking around I got the thing to work! So for future reference here is what I did. You cut the white wire, but the thing is there are two white wires, but the connector is numbered so you cut the white wire on pin 5 of the connector. To configure the circuit you set link 1 to X link 3 to X and Install R1, but don't install R2. And that's it! My speedo used to be 25% out but now it is near spot on. I am borrowing a GPS off a mate and will fine tune it in the next few days. Woohoo! :