LS SWAP - DBW - Cruise Control

[MarkN]

LS swap – DBW – Cruise control

With the engine swaps I have done in the past I have always attempted to make the driving experience as much as original as possible (other than the HP/torque and exhaust sound/volume changes). Things such as dash lights and gauges, gear selector display, and in this case cruise control should work as designed. My goal for this particular project was to adapt the existing cruise control lever to work with the GM DBW cruise control signals. As you may know the GM – DBW cruise control is very simple to setup using a couple of switches (1 SPST for the on/off, and one momentary SPDT for the set/resume/accel/coast function). However, the Lexus/Toyota signals on this series of vehicles and others in this time range use an analog signal to control the cruise control. This analog signal uses a series of resistors to signal the cruise control ECU to make the requested changes. To adapt the factory lever to the GM control we need to use a ADC (analog to digital convertor).

My first attempt to make this work was to utilize some of the existing functions in the Lexus/Toyota cruise control ECU. I used a LM339N voltage comparator to create my ADC. First I bread boarded the basic circuit.

Then I put the circuit together…

This was a failure… I attempted to use some of the functionality in the Lexus/Toyota Cruise Control ECU. This was a bad plan.. The ECU was in failure mode due to not having all the inputs from the factory Cruise Control process. Basically the on/off function was not working.. Lesson learned…

 

[MarkN]

Attempt #2..


Utilizing the same principals as in the first attempt I started again… Still use the LM339N as the core to my ADC. As you will notice this version has more pieces. 4 additional relays to convert the Lexus/Toyota momentary on/off switch to a latched on/off switch, and an additional potentiometer (and associated relay) to handle the cancel command.

Success…

 

[MarkN]

Attempt #3

However… I never could quite debounce the momentary switch to latched relays. If the cruise switch was off the relays would buzz like crazy. As long as the cruise was on (not engaged, but on) everything worked fine. In addition it took a little bit to adjust each potentiometer. After attempting to debounce the switch I decided it was time to move on… so onto version #3


I have some back ground in programming, so I decide to investigate microcontrollers to see if they would work in this process. It is what I should have done in the beginning. It is much easier to make this work from a software perspective than from a hardware one. It is much more configurable. I decide to use a PICAXE 18M2. I could have done it with a 14M2, and maybe a 8M2.. But I wasn’t sure how much I/O



Unfortunately I didn’t get to many pictures.. but I do have the wiring diagram and the code…

This worked extremely well… Worked the first time… it can easily be adjusted in the code.

This is most likely applicable to LS swaps only. However, I do believe it could be used to adapt most control signals in any engine swap. The technology is very powerful and easily adapted to handle most signal conversion processes. In fact I am looking into using this system for other signal conversion.. Tach, Speedometer, gear selector display, remote start, security system.. etc..

Please let me know if you have any questions..

 

[mikedamageinc]

I applaud your work, you obviously know your way around schematics and breadboards but why keep it simple. Modify the Toyota switch to send 0/1 hi/low signals instead of the analog. I am working on the same thing back burner for now but currently looking at a similar project on my Camaro. I am modifying a newer replacement steering wheel with controls to match that of my car. When it comes down to it, they are just simple switches that either activate an on/off signal or go through resistors to make an analog signal.

 

[MarkN]

I applaud your work, you obviously know your way around schematics and breadboards but why keep it simple. Modify the Toyota switch to send 0/1 hi/low signals instead of the analog. I am working on the same thing back burner for now but currently looking at a similar project on my Camaro. I am modifying a newer replacement steering wheel with controls to match that of my car. When it comes down to it, they are just simple switches that either activate an on/off signal or go through resistors to make an analog signal.

After looking at the switch and how it is constructed it was definitely easier to do this. In addition the Cancel function on the Lexus is not a option on the GM DBW cruise control. It could be done with additional hardware, but it was very easy to do with this solution..

 

[mikedamageinc]

Oh true, GM doesn't have the cancel option, would be nice if they did. So is this something that can easily be reproduced?

 

[MarkN]

Oh true, GM doesn't have the cancel option, would be nice if they did. So is this something that can easily be reproduced?

Yes and No... Currently I pulse the 12V on to the GM DBW to low for 1000ms... then back high.. This kicks the Cruise Control engage off. However, it also resets the stored speed, therefore the resume will not work (you will have to reset your speed). A better approach is to use the stop light wire to the GM DBW. This is the approach I will use on the next version. It will require a diode to prevent feed back to the brake light circuit and a resistor to pull down the voltage on the GM -DBW stop light wire (normally this would be pulled down by the brake light blubs going to ground).

 

[Golgo13]

Dude, now this is TECH. Finally!
Thanks for the great write-up so far and keep it coming!
I'm really happy to read something not related to tire/wheel/lift size!

 

[MarkN]

Dude, now this is TECH. Finally!
Thanks for the great write-up so far and keep it coming!
I'm really happy to read something not related to tire/wheel/lift size!

Thanks

 

[alia176]

I have some back ground in programming, .....

Yeah, no s***! Nice job on the documentation. That micro-controller looks very versatile.

I'm curious, can an Arduino be used for this as well? I'm not too hip on this stuff!

 

[JeepinPete]

Very nice! I'd be interested to see it applied for the tach signal and speedo correction. I've upped the tire size on my truck, the speedometer is 20% off...

 

[aae42]

Dude, now this is TECH. Finally!
Thanks for the great write-up so far and keep it coming!
I'm really happy to read something not related to tire/wheel/lift size!

Very nice! I'd be interested to see it applied for the tach signal and speedo correction. I've upped the tire size on my truck, the speedometer is 20% off...

noooooooooooooooooooooooooooooooooo

 

[MarkN]

Yeah, no s***! Nice job on the documentation. That micro-controller looks very versatile.

I'm curious, can an Arduino be used for this as well? I'm not too hip on this stuff!

Thanks

Not that familiar with the Arduino, but if it has 1 analog input, 1 discrete input, and 4 discrete outputs it should work.

 

[MarkN]

Very nice! I'd be interested to see it applied for the tach signal and speedo correction. I've upped the tire size on my truck, the speedometer is 20% off...

Thanks

I think it could be done.. but I am using Dakota digital signal converters for both the tach and speedometer now (like $80 a piece for them).. so it might be awhile before I work on those functions.

 

[MarkN]

noooooooooooooooooooooooooooooooooo

????

 

[ALX4X4]

Please make one that will work for my factory manual with no cruise(factory) so I can run cruise with DBW and manual. I need stalks and the lot with no real options in sight from here.....

 

[My4x4FJ40]

very nice write-up As I am doing 05 lq9 drive by wire I'm wanting to usethe factory lever would you be willing to build one for me.also by chance do you have the 3fe wiring pinouts for a 91 fj80 that integrate with the LS harnessfor the two connectors behind the glove box if you've done this build before I would greatly like to see a link to it.

 

[MarkN]

Please make one that will work for my factory manual with no cruise(factory) so I can run cruise with DBW and manual. I need stalks and the lot with no real options in sight from here.....

Not sure how the dbw cruise works with a manual.. I assume that the clutch has to have an input into the process. as far as a stalk goes you could use a SPST and SPDT rocker switches. I did this for awhile on mine. I mounted them on the left side of the dash near the light switch.

 

[MarkN]

very nice write-up As I am doing 05 lq9 drive by wire I'm wanting to usethe factory lever would you be willing to build one for me.also by chance do you have the 3fe wiring pinouts for a 91 fj80 that integrate with the LS harnessfor the two connectors behind the glove box if you've done this build before I would greatly like to see a link to it.

Thank you.. to be honest I don't really want to get into the business of building these for others.. I would be willing to help with a parts list, diagram, even the source code.. I just don't really have the time to get into this business right now. I think I might have the pinout for the two connectors you mentioned.. but my guess is that my 97 Lexus may be different than the 91

 

[RockJock82]

Would this work with the GM 411 to e38 PCMs? I know the later model GM motors use the BCM for cruiser functions. Great work!