[goelvaibhav]

Hi Guys

This is my first project. I have a Maruti Suzuki Swift VXi.

I aim to develop a RGB LED Circuit that will be installed inplace of the current orange light in the front instrument panel, which would change its colour (almost infinite colours possible) depending upon the engine RPM (Can act as a shift light also).
I am good in electronic circuits.

I need help from you guys to suggest me from where to take the RPM signals.

I beleive the ECU in the car has seperate port points that directly link to the tachometer. If yes:
-Where is it located (sorry im new)?
-What voltages does the signals have?
-The model/part no of the ECU, so that i can look up the net for its datasheet.

Thanks
Vaibhav

[bhp_maniac]

Originally Posted by goelvaibhav

Hi Guys

This is my first project. I have a Maruti Suzuki Swift VXi.

I aim to develop a RGB LED Circuit that will be installed inplace of the current orange light in the front instrument panel, which would change its colour (almost infinite colours possible) depending upon the engine RPM (Can act as a shift light also).
I am good in electronic circuits.

I need help from you guys to suggest me from where to take the RPM signals.

I beleive the ECU in the car has seperate port points that directly link to the tachometer. If yes:
-Where is it located (sorry im new)?
-What voltages does the signals have?
-The model/part no of the ECU, so that i can look up the net for its datasheet.

Thanks
Vaibhav

Wow... That will be a great one. Love the idea. The easiest method to take rpm signal will be the tacho itself I guess. Not sure though, but I've seen in my previous Xeta that the voltage was in the range of 0-5 V. The lights may start with a pure blue which will turn warmer and warmer to red as the rpm goes up. How about that? Regarding the ECU details, the easiest way will be is to get in touch with an A.S.S friend of you.

[shyamhegde]

This is an excellent idea you have come up with.

Also keep an option to control the color manually, in case if the automatically changing color of the panels becomes disturbing during long drives in night.

[bejoy]

Check this link for ECU wiring details.
2004-present Suzuki Swift Workshop Manual

May not be the exact model, but you would get some clue about the connections.

But instead of tapping the signals from existing wiring, why not use OBD to get RPM reading. It may be an overkill for this application alone and might jack up the cost a bit, but you will a clean system and plenty of future upgrade possibilities.

[goelvaibhav]

Thanks for your replies.

@bejoy: I checked the manual, it shows that the instrument panel has its own microcontroller which communicates to BCM via CAN protocol. There is no direct ports/points on the ECU.

I searched this forum, but could locate what protocol does maruti use for OBD and what would be its approximate cost.

I can make my own OBD using a microcontroller (need protocol details), but that would mean investing a lot of time and effort.

I want to start off with an easy project, so taking the RPM signals from the tacho itself sounds like a good idea.

Will head to my mechanic to open up the panel.

Will keep you guys updated..

Cheers
Vaibhav

[auto-one]

Nice idea, goelvaibhav. I have always toyed with the idea of having multi - coloured lights for the instrument panel / Music system / Multi information displays ( that come in today's cars ) .
Iam not into electronics so pardon me asking , but is it possible to use multi - coloured EL ( electroluminiscent ) displays / lights for the instrumentation?

[goelvaibhav]

I think you can use those lights provided they run on <=12V, which the car battery supplies. Otherwise you ll have to step up the voltages which is not a good idea.

You can have manual or automated lights depending upon your requirements, you just need a small pcb circuit that can take care of all that.

And actually, I am trying to do the same, I just need the signals, the circuit is already ready which can take 0-5V as input.

[ghpk]

I had this idea but don't find much time to give this a try.
If you wish you'll need to make a PIC (programmable I.C.) based circuit to do the same.

check youtube for moodlamp, its a RGB L.E.D. Based lamp which cycles colors on pre-defined combinations and gives a great looks, You can also make it stay on some color.

however the toughest part you would need to go through would be controlling colors with RPM, i think you can look for circuit idea from some bajaj bike, I don't remember the exact name but its speedometer dial and needle changes color depending on RPM.

Easiest way out i can think of is, have 2 RGB setups in the instrument panels, where one is controlled by a mood lamp, and other one with the tacho-meter kinda circuit.

[goelvaibhav]

Hi

I got the instrument panel opened. The circuit has 4 stepper motors : tacho, speedo, fuel and temp.

I thought the tacho would be a completely different unit, but its not. It is almost impossible to get the rpm signals from the circuit as shown below. There is a microcontroller which I think receives the data from ECU/BCM and then generates RPM signals.

How do I proceed? Is OBD the only option? If yes, where do i get it?

Regards
Vaibhav

[bhp_maniac]

Originally Posted by goelvaibhav

Hi

I got the instrument panel opened. The circuit has 4 stepper motors : tacho, speedo, fuel and temp.

I thought the tacho would be a completely different unit, but its not. It is almost impossible to get the rpm signals from the circuit as shown below. There is a microcontroller which I think receives the data from ECU/BCM and then generates RPM signals.

How do I proceed? Is OBD the only option? If yes, where do i get it?

Regards
Vaibhav

If you're sure all are stepper motors, then you can use the driving voltage as an input to your circuit. From the circuit lay out I think the driving voltage can be taken out as you wish.

[goelvaibhav]

@bhp_maniac

Im sure those are steppers motors. Now, you cannot just take the driving voltage from the circuit, since stepper motors work on a different principle.

For eg, if your rpm increases from 2000 to 3000, or from 3000 to 4000, the needle needs to rotate say 10deg, then the circuit will generate an exact signal, irrespective of the initial value. Also, the motor has 4/5 wires depending upon whether its bipolar or unipolar. It will be tough to track all the 4/5 wires and signals and then to interpret.

I think going with the OBD will be a better option. Can someone shed some light on the same, where do i get it, can i make it myself (CAN protocol on which maruti uses,etc).

Thanks
Vaibhav

[bhp_maniac]

Originally Posted by goelvaibhav

@bhp_maniac

Im sure those are steppers motors. Now, you cannot just take the driving voltage from the circuit, since stepper motors work on a different principle.

For eg, if your rpm increases from 2000 to 3000, or from 3000 to 4000, the needle needs to rotate say 10deg, then the circuit will generate an exact signal, irrespective of the initial value. Also, the motor has 4/5 wires depending upon whether its bipolar or unipolar. It will be tough to track all the 4/5 wires and signals and then to interpret.

I think going with the OBD will be a better option. Can someone shed some light on the same, where do i get it, can i make it myself (CAN protocol on which maruti uses,etc).

Thanks
Vaibhav

Ok, I think Suzuki vehicles are not directly OBD compatible, as they work on their own protocol. I have not seen any successful persons on T-BHP who have done this. I still believe, decoding the stepper motor control will be a feasible thing to do.

[im_srini]

Originally Posted by goelvaibhav

@bejoy: I checked the manual, it shows that the instrument panel has its own microcontroller which communicates to BCM via CAN protocol. There is no direct ports/points on the ECU.

That's true...



...but, I did not get the "direct ports/points on the ECU" bit.

From the service manual, I can see there are 3 ways to get the RPM signal:

A) CKP - Crankshaft position signal



B) CMP - Camshaft position signal



C) EPS - Apparently, the EPS also needs engine RPM



The harness-side pin-out diagram of the ECM...

[goelvaibhav]

@im_srini: Thanks for the info. I think I dont have the correct manual. Can you post/host it or give me a download link.

Thanks
Vaibhav

[im_srini]

Originally Posted by goelvaibhav

@im_srini: Thanks for the info. I think I dont have the correct manual. Can you post/host it or give me a download link.
Thanks, Vaibhav

Hi Vaibhav,

No, I did not download the service manual - I have a hard copy. I sourced said service manual from my regular Maruti-Authorized-Service-Station. If you require any specific information, please update the thread - I'll put it up if I can find it in the manual...