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Discussion Starter #1 (Edited)
Happy to say I've improved on the other solder pad conversion method and got this working spot on on my 180kmh speedo.

No matter what you read elsewhere, leave J2 and PESL alone, as messing with them causes the ecu and HICAS to only see half the true speed. Some cars have J2 already bridged, others don't, so messing with it can affect speedo sweep. If it's there it's there, if it's not it's not, just leave it alone. They're set like that for a reason, so don't touch them. Before anyone starts arguing, I've proved this for certain via consult.

Remove J4 only, as this converts the odometer reading to mph by altering the signal by 1.5. The remaining 0.1 difference appears to be taken care of by my size of wheel. The signal to the ecu and HICAS remains unchanged.

Next, I calibrated the sweep of the speedo with the pads. Adding solder to the various pads reduces speedo sweep, and the lower the pad number, the less it influences the sweep. Mine's a manual with 18 inch wheels and 35 profile tires, so I bridged pads 3, 4, 5, 7 and 8. If any others are bridged, clean them off so there's no continuity.

Here's a couple of pictures to show you what I'm on about doing:

Here's a picture of the back of the speedo unit before I modified it. The areas of interest are circled in red, the J4 link and the calibration pads.


And here it is afterwards, with J4 removed to convert the odometer to clock up in miles, and the relevant calibration pads soldered to change the speedo sweep into MPH for a 180mph dial on a manual gtst with 18" wheels and 35 profile tires:


Doing this has resulted in an indicated speed maybe 1 or 2 mph above what the gps reckons, the odometer and trip counter is near enough spot on, my abs still works perfectly and the ecu and HICAS both get correct speed signals. Far safer than the HICAS thinking you're going half the speed and it deciding to turn the rear wheels when they shouldn't.

The only downside is I assume the speed limiter is still in place. Can't prove it as my car is currently riddled with flatspots above 5k rpm until I get a new ecu. But the way I see it, if people have kept their skyline standard then they aren't likely to need to exceed 112mph, people who DO need rid of the limiter are likely to have modified skylines, so would have an aftermarket ecu anyway. A chipped or aftermarket ecu won't have the speed limiter anyway, hence why I don't see it as an issue.

EDIT:

A note for GTR owners is you need to miss pad 3 out to account for your different gearing. So you guys need to remove J4, and have only pads 4, 5, 7 and 8 bridged. All other numbered pads left open. Turns out ths is exactly the same as the genuine UK spec R33 GTR MPH speedo then.

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Discussion Starter #3
Works perfectly as described fella. I could even do it for you if you're close enough. If anything it's easier to do than the other method, since you don't have to break the PESL track or solder a new link onto the PCB. You literally just remove one link and add solder to the calibration pads as necessary.

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Good to meet you today Dan, interesting results after plugging your laptop in & seeing the HICAS numbers. Might be worth adding details of the unit required & the software so others can check that all is working correctly before & after the mod.

Alan..
 

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Discussion Starter #5
It's just a consult cable, readily available on ebay. Mine cost 16 quid delivered, and the various software you can use can be found online. I recently started a consult software thread asking for recommendations, and at the moment I know of conzult, datascan, ecutalk, etc. Each of these all confirmed my suspicions of the other method on your car today, and also the success of my own.

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Well you only need to fool the ECU above 112 mph and for sure the front steering 'feel' does not change above this speed, and it's I think a considered fact that the HICAS 'map' does not vary above this speed.
 

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Discussion Starter #9 (Edited)
That's what I think too, but others disagreed. If it was like that then there would be nothing at all wrong with fitting a 5 wire clamping delimiter, but that apparently isn't ideal. My way means it always knows the correct wheel speed, the only drawback being the limiter still in place. But since this is controlled by the ecu, anyone keen on going quick or on a track will have a modified car and aftermarket ecu anyway.

At the very least it'll save buying a 5 wire converter chip, and it's one less thing to go wrong.

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cheers for posting this up chap, not directly related but I have a set of 180sx clocks and 200sx clocks so will see how similar they are - I have a feeling the kouki 180sx may be similar in design to the later cars - S14/R33 etc so I'm hoping to get rid of the five wire thing that's on the car at the mo.

I'll post up some pics to see if they're similar in any way.
 

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Discussion Starter #13 (Edited)
I've driven a couple when I was looking to buy mine, and yes imo they didn't feel right when converted with the other method, though couldn't put my finger on it at the time since I had no prior experience of what they're supposed to be like. I've also been in phaeton's car after he did the other mod, the same day I'd done my speedo my way. He doesn't trust the handling as it's twitchy, and I confirmed it was only seeing half the true speed via consult. This resulted in his car's power steering being too light, and the HICAS is reacting at the wrong speeds. My car doesn't have this problem. And makes the odometer count correctly. You can still cut the pesl link with my method of course, but doing so DOES affect the HICAS and power steering so I don't advise it. Can't remember if cutting pesl also alters the signal to the odometer too. As I keep saying, it's better to derestrict the car by changing the ecu, since chances are people wanting to go quick would need to anyway.
 

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Discussion Starter #15 (Edited)
So not working as intended. If what you say is correct, and it only activated at above 120mph with the other method, it would still alter rear steering angles on the assumption you're only doing 60mph. Mine would operate as intended, at the correct speeds.

The power steering of course is lighter the slower you're travelling too. So if you're doing 50mph but the car thinks you're doing 25mph, it'll make the steering too light.

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can ypu post up a pic of yours after you did it to compare it to the uk gtr speedo? my car has aftermarket ecu and a chip converter fitted but recently my speedo has started moving with the revs?? strange any ideas?? cheers
 

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When i bought my car already have a chip to mph. So should i remove it and do this as i already have a power fc?
also, do you know how to fix the rev counter? as mine is going nuts. Read on a few thread as people try to fix it, but after a while it goes nuts again.
 

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Discussion Starter #20
When i bought my car already have a chip to mph. So should i remove it and do this as i already have a power fc?
also, do you know how to fix the rev counter? as mine is going nuts. Read on a few thread as people try to fix it, but after a while it goes nuts again.
In my opinion, yes. As then the ecu and HICAS will see the correct speed even beyond the 112mph limit the car used to have. If your converter chip has 4 wires these control units will see the wrong speed all the time. If your converter is a 5 wire one instead, they'll see the correct speeds up to about 110mph, but it will then prevent them from seeing anything higher.

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