Ranger Mods

With standard tyres the RCM module sends the true speed from the wheels sensors to other modules within the vehicle and from past measurements it was spot on to GPS speed.

The instrument cluster is programmed to read approx 4 kph slower than actual true road speed. It covers the manufacture slight inaccuracies as our laws in Australia are so tight with speed. This is in the firmware and cannot be modified. What you see is an illusion as such.

The DTE in the cluster is based on the fuel going through the injectors or pump and KM travelled, this is based on true road speed with signal from the RCM. (Restraints Control Module)

So DTE is based off real unmodified data and the mechanical and digital speedo is based off unmodified real data then minus 4kph.

I hope that kind of makes sense.

rusty-pie wrote: ↑Tue Aug 15, 2017 10:04 pm By the way, have you found any way to use a diameter larger than 0977 without throwing out fault codes?
Cheers.

No we cannot do it. In the PCM there is an allowable tolerance between this and this and if it falls outside of these parameters then the PCM with throw a fault. I have a feeling it is in the TCM too or the TCM asks the PCM if it's allowable as you can get them to both fault if you push it far enough.

In the US for certain models you can buy modules that make a programming change in the PCM to widen these parameters and then allow a increase in tyre size.

The only way to modify our PCM's is to crack them open and unlock the MCU then make the required changes. Changes after that can be completed throught the OBD port. This may or may not change in future but will come down to our European tuners that seem to have more time than others.

European hardware appears to be locked down a lot more than US hardware.

Cheers Stewart, it makes perfect sense and that is exactly what I meant about true vs indicated speed.

I believe though that you meant to say that the introduced error is in eccess, the speedo reads 4 km/h faster (ie shows 104 at 100 km/h) than the real speed to ensure that speed limits are not exceded unintentionally because of meaurement errors. I'm sure was just a late night typing error.

I'll try with the 0977 value tomorrow and check how closer to the GPS speed I can get to. Hopefully I will still be able to get a little margin in excess between gps and indicated speed.

Sorry yes you are correct. 96 = 100, 100 =104 etc. On a long trip I set cruise control to 107-108 and have gone through many cameras etc. With no issues. They would see I'm doing 103 which is within the legal limit if I look at it in a technical view.

Thanks for the pickup. Time to go and rest my head, tired and typing on the phone does not help.

With 265/70 17 I'm within 1kph of what the vehicle was factory when set at 0977.

Good luck and give us a heads up on how you go and with what tyre size.

Hi Stewart, what kind of fault is shown if I enter an invalid value, engine check light?
Entered 0977 and no error messages so far, will go for a spin later on to compare speedo with gps speed.

Yes, you will get an engine check light, along with PCM fault code and sometimes a TCM fault code. I know of no one that has done the change and stayed under 0977. Only one had an issue but I would say the existing fault code had not been cleared.

The PCM will stay happy at that.

I have changed the value from 0934 to 0977. At 60 km/h, the speedo went from being spot on to the GPS speed to 1 km/h in excess of the GPS speed. Tyres are 2" taller than stock.

By the way, the decimal equivalents of the hexadecimal values do not seem to quite match the corresponding circumference lengths, what is the exact relationship between them?

They are right. There is a margin factor built in that you have not accounted for that Ford's BCM does account for. It's based on 97.6% or similar, I cannot remember off hand.

Shame you didn't get more of a change. I thought Gerry's tyres were 2inch over and he seemed to get a better end result.

saeb wrote: ↑Wed Aug 16, 2017 10:53 pm They are right. There is a margin factor built in that you have not accounted for that Ford's BCM does account for. It's based on 97.6% or similar, I cannot remember off hand.

Shame you didn't get more of a change. I thought Gerry's tyres were 2inch over and he seemed to get a better end result.

Mine are 1 inch larger Stewart, I'm running 285/65/17. I'm assuming my distance is somewhere near correct as my speedo again shows about 4 kph fast.

saeb wrote: ↑Wed Aug 16, 2017 10:53 pm They are right. There is a margin factor built in that you have not accounted for that Ford's BCM does account for. It's based on 97.6% or similar, I cannot remember off hand.

I wasn't questioning that your figures are correct, just wondering if it was purely a multiplicative correction factor of something more complex.

Makes sense, effective tyre radius at the contact patch is smaller than half the nominal diameter. It seems to be 96.7%

I need to do this. Just got done for 112 kph. Speedo was showing 104. My tyres are 285 70 17. $300 and 3 points. Argh

Hi Stewart, have you tried many values above 977? I was wondering if maybe there are some specific values above 977 which might be allowed and others are not?

I really would like to be able to set the correct wheel diameter, not concerned too much about the speedo and fuel consumption calculation, but today I had the first long-ish motorway journey with the taller tyres and I've got the feeling that the adaptive cruise control is not as good as before at keeping the set distance with vehicles in front, especially when they brake......

rusty-pie wrote: ↑Sat Aug 19, 2017 10:36 pm Hi Stewart, have you tried many values above 977? I was wondering if maybe there are some specific values above 977 which might be allowed and others are not?

I really would like to be able to set the correct wheel diameter, not concerned too much about the speedo and fuel consumption calculation, but today I had the first long-ish motorway journey with the taller tyres and I've got the feeling that the adaptive cruise control is not as good as before at keeping the set distance with vehicles in front, especially when they brake......

First post on this thread "Maximum size in hex in the BCM the Ranger will take before throwing PCM and TCM codes is 0977." No ifs or buts... It is a tolerance margin between **** and 0977, nothing below and nothing over. I have not looked at the smallest size and as I have never had a reason. It will also get to a point where the BCM will not even allow the input.

I see nothing CCM in relation to your problem. It's possible that you need to do a service realignment of the Radar Sensor. I think the latest version of Forscan supports this now. The only thing that will effect distance is the radar module.

I've tried 09D2 which is my exact tyre size and I can still input that.

The change in behaviour of the adaptive cruise control happened overnight when I changed the tyres so I'm pretty confident is related to that. To be more specific, when the car in front brakes suddenly (e.g. traffic jam on the motorway) the Everest slows down too gently at first and then has to apply the brakes more abruptly in the end as it gets too close to the car in front, rather than slowing down more noticeably initially and not having to brake all of a sudden in the end. I would be very surprised if the control algorithm of the ACC does not considers speed as one of the parameter to calculate the amount of braking necessary to maintain the set distance and speed, so in my opinion the ACC thinks the car is slower than it actually is and applies less brakes than required at first.

Are you aware of any other way (not forscan, e.g flashing the control module) of removing the limit on the tyre size, or plug in module that can compensate for the tyre size?

Yes you are right you can enter that although with a DTC. There is nothing to suit the Euro PCM that can change it. US yes they can do there changes to the PCM with a plug in but unfortunately we do not share the same PCM.

You could talk to an engine tuner but they will need to crack the PCM open first to unlock before writes can be made.

I cannot say I notice any difference in the braking on my vehicle.

I will see if there is any further in a manual I have and if so will post up.

rusty-pie wrote: ↑Wed Aug 16, 2017 8:37 pm I have changed the value from 0934 to 0977. At 60 km/h, the speedo went from being spot on to the GPS speed to 1 km/h in excess of the GPS speed. Tyres are 2" taller than stock.

Made the tyre size change yesterday and maxed it out at 0977 for my 285/65-18s they I fitted yesterday. My GPS speedo (app on the phone) says 1 - 2km/h difference. Seems to fluctuate a bit but I put that down to me trying to drive while watching the speedo and phone and latency for the app to update. Basically not enough of a margin to worry about in terms of getting done for speeding.

I'll scan for any new DTCs when I get home tonight to just to make sure as I checked before making the change that they were all clear.

I did notice one odd one which I'll check again later. When reversing, the direction/position indicator overlay on the camera image no longer change as you turn the wheel. I can't say for certain they were working immediately before the change but I'm not sure what else might've caused it. Anyway, I'll check and see if it continues to do it and create a new thread.

We may try to implement a feature in Forscan to fix the Tyre size DTC's.

It would be a test and see from a different model vehicle. Doubt it will be implemented to test until all the other changes I have put forward are implemented.

That's great news Stewart, keep us posted!

saeb my numbers show 726 -12-01 -0175 - 0938 - 5148

Is this the correct? and am i changing 5148 to 0977?

thanks

benmorris91 wrote: ↑Sun Sep 03, 2017 5:06 pm saeb my numbers show 726 -12-01 -0175 - 0938 - 5148

Is this the correct? and am i changing 5148 to 0977?

thanks

No.

Change 0938 to 0977.

saeb wrote: ↑Sun Sep 03, 2017 5:15 pm

benmorris91 wrote: ↑Sun Sep 03, 2017 5:06 pm saeb my numbers show 726 -12-01 -0175 - 0938 - 5148

Is this the correct? and am i changing 5148 to 0977?

thanks

No.

Change 0938 to 0977.

thanks for that, its giving me a box saying incorrect checksum of data entered
Continue anyway?

thanks

Yes continue and check your PM

hi guys just some info.

stock Tyres
gps 107 - speedo 110

285x70x17
gps 113 -speedo 110
new trip km on way home 13km -gps 14km

Q. if I change the Tyre size will that give me in the middle range in the speed and bring the trip back down?
was there also a ultraguage setting for Tyre sizes for accurate speedo?

cheers

Should be able to knock about 4kph of it with tyre size change, so it would be at least closer to your speedo.

Not sure the adjustment is built into UG but worst case you could make a custom MXgauge for the speedo and with the calculations minus the amount you need to get it correct again. Down side is you loose one custom gauge.