3.7L V6 QT1 to QT2 Conversion.

[Matt]

I hear ya. I'm trying to knock it out before the kids get old enough for sports and I really have no time!

[ScorpionCrawler]

This has been a fun read, I'm maybe getting 30% of what you are saying but am hoping for the day that you say it's dialed in the way you want it to be.
Great build, great thread, keep up the good work and info and GOOD LUCK!!

[Matt]

Ok there's definitely a few options but we have to do a bit of homework to determine which are viable. It all depends on what the computer is doing with the signal. If the computer is "dumb" and only cares about pulses (on/off/on/off/etc) then there are some simpler options. However, like eluded to in the Dakota Digital link, the computer may be analyzing the entire signal- not just PPM but other parameters such as pulse width which would be affected by some simpler conditioning methods.

So we'd have to check the schematics to see where the speed sensor signals are going (which modules) and try to figure out what the module(s) are looking for.

**something quick/fun to try that would only help someone with controllable lockers; what would happen if all 4 sensors are unplugged? Wondering if that would prevent limp mode and just throw ABS/TCS lights, thereby allowing you to wheel in 4-low?

[cmdr jim]

Here is a bit more information from the service manual about the Wheel Sensors:

SENSOR-FRONT WHEEL SPEED
DESCRIPTION
A wheel speed sensor is used at each wheel. The front sensors are mounted to the steering knuckles. The rear
sensors are mounted at the outboard end of the axle. Tone wheels are mounted to the outboard ends of the front
and rear axle shafts. The gear type tone wheel serves as the trigger mechanism for each sensor.
OPERATION
The sensors convert wheel speed into a small digital signal. The ABM sends 12 volts to the sensors. The sensor
has an internal magneto resistance bridge that alters the voltage and amperage of the signal circuit. This voltage
and amperage is changed by magnetic induction when the toothed tone wheel passes the wheel speed sensor. This
digital signal is sent to the ABM. The ABM measures the voltage and amperage of the digital signal for each wheel.

Not sure what this all means.

[Matt]

That's not really saying much...

The sensors convert wheel speed into a small digital signal.

I'm sure you know this already, but others might not.
This just says what the sensor does.... wheel speed means the tone ring is rotating, as it rotates the sensors reads that and creates the digital signal which is merely a square waveform.

The ABM sends 12 volts to the sensors. The sensor has an internal magneto resistance bridge that alters the voltage and amperage of the signal circuit. This voltage and amperage is changed by magnetic induction when the toothed tone wheel passes the wheel speed sensor.

This is just the written description of the hall effect sensor. The magnetic field changes as the teeth of the tone ring pass.... on/off/on/off/on/off/etc. The change in magnetic field takes the standard input voltage and creates a fluctuating output. It's this output (voltage and magnitude) that we need to figure out..

This digital signal is sent to the ABM. The ABM measures the voltage and amperage of the digital signal for each wheel

The bold is the important part.... the voltage and amperage measurements indicate the module is concerned with more than just the number of pulses in a given period of time. This would make sense now that I think about it since there are DTC's for high/low sensor voltage....

[Matt]

There is a way to tap into the signal.... but that's the easy part and doesn't answer the question of what the ABM is doing with the signal. If its just counting pulses there's no problem, whereas if its analyzing the waveform (probable for present day electronics) then we'll have an issue.

I guess the only way we'll really know is to test it out like you drew up......

[cmdr jim]

I think you are right, testing it may be the only way....another $80.

Getting back to your manually locking ELSD question. Keep in mind, I don't have all the electronic features to lock and unlock the differentials as you do with the FDCM. The ELSD is electro-hydraulic operated, and applies a pressure to a clutch pack. Your Jeep uses a PDM to control voltage to the solenoid to vary the pressure on the clutch pack and does this as required for the different inputs it is receiving from the wheel sensors, engine, transmission, etc. It also monitors the resistance to determine how hot the differential is getting and will back off on the useage if it gets too hot. A lot is going on there.

I have done a number of test on a soleniod out of the ELSD and it is high temperature rated, over 350 degrees F. I have tried to kill it with time, but at over an hour of on time and temperatures stabilizing around 300 F, I couldn't. I started testing with an adjustable PDM but found out shorty, it's not needed if all I'm going to do is apply full pressure to the clutch pack. For my use, it's really quite simple. I am going to use a 12vdc voltage regulator and a relay and switch. The solenoid pulls under 1 amp at 12vdc (I could probably get by without the relay) Then just turn it on with the switch when needed and shut it off when not. The key here is not to keep it energized for more than 20 to 30 minutes to stay away from any heat issues.

If you wanted, I would start a test by just unplugging both your front and rear ELSD solenoid wires and shut off Traction Control and see what errors you get. If you get some, plug the wires back in and drive it, see when the errors go away. If they do, your next step would be to find a DPDT relay or use 2 relays. I think you want to disconnect both the positive and negative wires going to the FDCM from the ELSD solenoid when powering it with straight 12vdc. Nothing getting back to the FDCM period.

In the picture I show the solenoid hooked up to a power supply, shortly after that picture I had to hang the solenoid from the desk or it would have burned the desk. I ran numerous tests and couldn't kill it with duration or temperature.

[Matt]

I was following you ELSD thread... I believe on the commander forum?

Agreed, there are a lot more limitations from my end. Probably worthy of a whole new thread.

Since its more of a "nice to have", I think energy should stay focused on the QTII tcase conversion. Not to mention, the results if your testing could be the solution for manually controlling the ELSDs on vehicles already equipped. In case the idea didn't already pop into your head..... we may be able to trick the computer in thinking one front and one rear wheel is slipping so it engages the diff. (Unknown would be if we get errors after diff is engaged and wheel speeds are still off.... lol another thread for that)

[cmdr jim]

Yup, on the other forum....

I ordered a SGI-5 and am planning on testing next week some time. I think at first I will set it up to run on only one wheel sensor. I can have it condition the signal at a ratio of 1 to 1. If it functions properly I'll add in the other 3 wheel senors and test Low Lock.

My email back from Dakota states there are two possible outputs from the SGI-5:

Technically all of the outputs on that unit are a square wave. *The difference on them being the A/C outputs are above and below ground (-6V to +6V), and the open collector outputs will be all above ground with voltage dependant on the pull-up provided (0V-12V if a 12V pull-up).

So as long as the ABM isn't looking for something other than these two types of input it should work....

[cmdr jim]

The SGI-5 came in yesterday, I hooked it up to a front wheel sensor and I can't get it to see a signal. I went through the troubleshooting section of the manual, I get a constant green light on the SGI-5, which means no signal. I tried all the changes suggested in the manual and could not get a signal from the wheel sensor. Also while running off the SGI-5 without a signal, the anti-lock brake error and no traction control lights came on immediately and stayed on until I reconnected the wheel sensor back to normal. My guess is the wheel sensor is sending a signal the SGI-5 doesn't recognize.
I think I'm back to setting up a wheel sensor to switch to when in Low Lock.

I have an email into Dakota Digital tech support.