Hall sensor alterations

Thread Starter

clarkie250

Joined Sep 16, 2023
6
Hi everyone,
So I'm not really technical with circuitry only what I've picked up along the way. I'm just a heating technician, mainly fault finding at its most basic form on electrics, voltage tracing etc.

So basically I want to install a remote start on my van and need to temporally disable the clutch sensor so the PCM thinks I have depressed the clutch. (I know what you are going to say....that's dangerous.) But my remote starter has other built in safety devices like neutral detection to stop it being started when in gear.
Unfortunately I have the hall sensor on my clutch system which senses the exact position of the clutch, it has 4 wires. As apposed tho the older cars that is just a 2 wire switch.

The wires for the senser are as follows:

  1. Cpp1- which is clutch pos at the top( I believe)
  2. cpp2- clutch pos bottom fully depressed.
  3. Signal wire which I believe is ground to pcm
  4. Vref voltage which is 5v DC shared with AC system.
I noticed that when my foot is NOT depressing the clutch I have like 0.8 V from the signal wire and cpp2 and when fully depressed it's around 3.8V, but noticed the engine will start at around 2.7v dc

How do I simulate the fully depressed action? Remember it's only temp, the remote starter initiates the trigger only on crank via a negative feed for a few seconds then a relay breaks the connection.

I've connected most of the wires via the gateway can/bus connections of the van. The clutch bypass wire from the R-starter would normally ground to the simple on off switch temporarily to bypass the clutch but obviously this setup won't work for the hall sensor. I think I can work it so I have a positive signal wire from the RS to the hall sensor if needed?
I wondered if I could just use a link from the 5v reference voltage supply using a diode plus a resistor to bring the voltage down a bit to the cpp2 to stimulate the 3-4v but i haven't tried it yet... thought I would speak to someone who knows more before I blow something up.

Heres the schematics for the sensor....

clutch sensor schematics from wiring manual, i cant find any details of the switch itself but i know the vref is 5v

Basically my question is which wire would I need to alter to achieve the trigger voltage, which I'm guessing is from 2.6v-4.8v on the cpp2 control wire ?? Do I need to add a resistor in there somewhere to bring the voltage down on the VREF (I have no idea really, this is what I've heard others doing but not sure it applies to my setup ) Or can I just link the VREF voltage straight to the cpp2 wire to give 5v?? Please help asap as this is the last step to completing the system. Thanks in advance. Chris
 

nsaspook

Joined Aug 27, 2009
12,318
...that's dangerous IMO. You need to have some sort of fail-safe (that the driver MUST activated before leaving the car) in the car that locks-out remote-start unless the conditions are safe.
 

Thread Starter

clarkie250

Joined Sep 16, 2023
6
Yes it does.
Firstly It won't start if it's in gear due to the neutral position sensor also it has another safety feature where it will only remote start if you enter reservation mode before you exit the van you must push brake, pull the hand brake and be in nautral.

so you got any ideas how to get around this ???
 

geekoftheweek

Joined Oct 6, 2013
1,102
The hall sensor for a clutch switch sounded a little off so I did a little poking around...

Ford commonly uses PWM signals for some of it's sensors and according to https://www.nburkediag.co.uk/ford-transit-clutch-pedal-faults the transit clutch sensor is yet another one. The voltage you are reading is an average and not a true picture of what is happening.

A simple voltage divider won't get you where need to be and it should cause a fault and not start at all.

Part of the reason is for checking signal integrity and another part is probably to prevent things like you want to do. If a signal is supposed to cycle between states, but stays one way or the other it's an easy way to tell there is something wrong.
 

geekoftheweek

Joined Oct 6, 2013
1,102
Yes and no to the solution.

Firstly It won't start if it's in gear due to the neutral position sensor also it has another safety feature where it will only remote start if you enter reservation mode before you exit the van you must push brake, pull the hand brake and be in nautral.
If that quote is all features built in to the remote start module itself then the easiest way would be to bypass the PCM and connect directly to the starter relay itself through another relay to prevent back feeding circuits.

Without a proper understanding of your module and how everything actually works I doubt anyone is going to give you a usable answer.

I am guessing you are trying to fit a remote start designed for an automatic into a manual transmission vehicle.
 

Thread Starter

clarkie250

Joined Sep 16, 2023
6
That's a shame....oh well it was worth a try.
Thanks for the advise.
Although I'm not technically advanced in circuitry, I'm not a complete novice with electrical wiring systems.
I designed and fitted my own harness for the remote starter system complete with fused, diode isolated starter interrupt relay, which is used for the natural safety/anti grind input.

I had already considered the option you mention direct at the starter, but was hoping for a less invasive approach, inside the vehicle.
So I should be ok with that, i have the wiring schematics as well.
But if anyone wants to give any advise i will certainty welcome it.

Btw I'm not saying I'm a expert but i wont cut corners and would consider myself meticulous and i'm fully aware of dangers.
its only to be used on freezing cold days outside my house so no danger to anyone but my house lol.

Basically my RS module has several programmable in/outputs which would need to be relay triggered to suit the desired current ratings. i have a programmable 30a 2nd starter wire spare so could use that.
thanks for the advise.
 

Thread Starter

clarkie250

Joined Sep 16, 2023
6
Quote "I am guessing you are trying to fit a remote start designed for an automatic into a manual transmission vehicle."

No it is designed for manuals aswell but they dont have any solutions for the clutch bypass for my van....now i know why.....
 

geekoftheweek

Joined Oct 6, 2013
1,102
I had already considered the option you mention direct at the starter, but was hoping for a less invasive approach, inside the vehicle.
I can understand that completely.

No it is designed for manuals aswell but they dont have any solutions for the clutch bypass for my van....now i know why.....
I'll admit I have never dealt with a remote start system, but I would think a modern day one would simply command the BCM to start the engine as long as certain conditions are met. Obviously that approach will take specific programming for each vehicle it's designed for instead of a universal unit.

One thing I do wonder is how will you deal with anti theft keys or do you already have a way around that?

Good luck at any rate!!
 

Thread Starter

clarkie250

Joined Sep 16, 2023
6
Yes there are several modules that work in conjunction with the PCM ( Power control module) including the BCM I have some software to adjust some ABD (as build data) coding changes i.e start/stop disable but the software isn't oem design level so it can only change basic commands.
Yes I've already bypassed the ignition PATS using the second key transponder which is only activated when the starter receives a command along with the alarm. Just 1 step away... the bloody clutch haha.
Ill have a good look at the starting system tonight and look at the best place to interrupt the start signal.
So could someone explain how the digital signal works ? Surely it can be simulated from the switch to the PCM???
Vref voltage in - then signal back? I even thought about. Buying a used switch and modifying that to use a temporary command output via the starter because the switch can be replaced, it's not like it's coded to my specific van.
Cheers for the advise so far.
 
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