Ranger Mods

I’ve found 3 different pids for engine coolant temp (DCU, OBDII, PCM) and battery voltage (BCM, APIM, SCCM). They show slightly different values, especially the battery ones.
Why this difference, and which one is the most accurate to monitor?

BCM will be the best to monitor as it contains all the BMS info.

Coolant use PCM

Component variations will be the main factor that with cause different readings. Components are made in bulk and to a price. Measure 5 different resistors with a good meter and you will be lucky to get the same value across them all. Sensors are pretty much the same, put 5 different stock rangers on a dyno and you will get 5 different results.

You will find coolant is also in the TCM but all modules pull the data from the PCM.

Thanks Stewart, makes sense.

Is there a PID which displays the speedometer speed? I've found a dozens pid's which display the "real" speed, but don't seem to be able to read the corrected speed displayed by the speedometer.

No, the actual speedometer speed difference is built into the IPC firmware.

OK. I have found a PID which shows the % of speedometer speed (seems to be % of 200 km/h), so was hoping there was one showing also the actual value. It would be very easy to do if the app had user defined gauges showing calculated/derived parameters.

Not sure why you wish want the wrong speed but find the exact difference between BCM speed and odometer speed with a GPS then change your math adding +4 or 4.5 or whatever on the end.

Without seeing the PID or any other relevant info I can not really add much to that.

Because my tyres are larger than 0977 and the "real" speed is wrong, the speedometer one is right.

I am talking forscan app here so unless I've missed something obvious in it, there is no math to change.

No, not in Forscan nor any other app. You could make a custom PID in Torque, OBDlink, SG or UG and do custom math if you are using one of these other packages.

The Forscan iOS app is great as it shows all the possible sensors but has a glitch that makes it unusable: the dashboard reset itself to no gauge every coupe of times I use the app. Am I doing something wrong?

How can I extract from Forscan the PID's math to be used for the OBDLink app? OBDLink is much more user friendly but it does not have most of the PID's I need.

Make a list of the PIDS and I will see if I have already worked out the math and if not slowly try and get them from Forscan team.

Have you sent an email to them to explain the issue you are having with the IOS app? If I send them fixes they are usually done within a day or 2.

If not send them an email, contact details on their site and fully explain the problem in point form. If they can replicate it then they will fix it.

Cheers, I've emailed them and they have already sent a possible fix which I will try tomorrow.

Out of curiosity, what is the procedure for working out the maths of obdlink custom pids, is it just a matter of comparing the obdlink and forscan values for a certain sensor reading and to interpolate an equation to match the same values?

No email received.

I think from memory when you test in OBDlink or Torque it will show the decimal figure in the response.

So say ACT, air charge temp

Response hex is 3D converted to Dec is 61. Ford IDS or Forscan is showing 21
Response hex is 3E converted to Dec is 62. Ford IDS or Forscan is showing 22
Response hex is 3F converted to Dec is 63. Ford IDS or Forscan is showing 23
Response hex is 40 converted to Dec is 64. Ford IDS or Forscan is showing 24

Looking at that I know that the temp is linear and their is nothing odd about it. It also stands out straight away that 61 -40 = 21 etc. So I know it is always -40 to display the correct figure.

Torque (A*256)-40 1 byte 61 dec -40
UG Math *0001 /0001 -FFD8 61 dec * 1 / 1 - 40 * 0 or / 0 can lead to issues so * or divide by itself.

That is a simple one as not all the maths are linear and in that case I try and log a range then in excel fill in the gaps, sometimes a chart can also be helpful. Some modules have more than one PID and can be high resolution and use 2 bytes where some will only use one and be low resolution or only require 1 byte.

UG and SG use the same math but both also have additional options /10 /100 etc. so when using the values other areas need to be looked at also. Torque and OBDLink also appear to use the same math.

UG does not support multi frame on some modules, an unreleased SG firmware version I have does and Torque and OBDLink also do. Some PIDS are returning 20 plus bytes of data. So you need to find out what the 10 to 20 different sensors may be at times.

MAP sensor high res is 7E022F40B uses 2 bytes where MAP sensor low res is 7E022F40B uses 1 byte. The maths are different for both.

I monitor the CANBUS with different software and hardware but the last time I did every PID in the BCM I spent about 4 hours at the vehicle and so far have spent about 8 hours doing calcs. This is unfinished and will continue again soon.

The idea was to enter all the PIDS into the desktop version of OBDlink but the software is not fully compatible I found out. I have lodged issues with the software developers but I do not expect anything in the next 100 years. We will see though as it is meant to be compatible. At some point I may just add them to a CSV and they can be imported that way.

As you can see it is very time consuming, I will be starting my next lot of Forscan additions in a few weeks so once I start lodging more of those I could hit them up for some calcs on odd ball items if I cannot figure them out. I generally try and give a fair bit before I ask for something from their own hard work. It has paid off though and is nice having some unreleased Forscan items items for testing and also the option to have them give test versions of specific things I want to try.

Cheers Stewart, very clear explanation, it’s pretty much what I was expecting.

I actually meant that I’ve emailed the forscan guys and they have already replied with a possible fix which I’m going to test in the next couple of days.

I’ll send the list of the pids I’d like to use in OBDLink later on.