SMT Dashboard Clock Wiring

crankshaft · April 10, 2004, 07:45

Hi;

Doers anyone have a wiring diagram or detailed pinouts for the main dash unit for the SMT ?

I am particularly interested in the Gear Indicator display and the protocol used to communicate between the ECU and the display.

Does anyone know if this is all controlled via a common bus between the ECU and the displays or if each display 'element' has it's own control wires ?

Any info would be appreciated.

Thanx

PeterC

mph · April 10, 2004, 10:18

Yes s:)

s:) Unfortunately no scanner handy. s:(

s:(

Looking at the diagram, the dash has it's own mini ECU. This controls the LCD directly. As for input, there's nothing marked SMT.

Connections from the Engine ECU to the dash:

A5 - Vane Pump Assembly with Motor (SPD Terminal), Engine ECU (SPD Terminal)
A15 - Engine ECU (SNWO Terminal)
A17 - Engine ECU (W Terminal)

B4 - Engine ECU (MPX2 Terminal)

C5 - Engine ECU (MPX1 Terminal)
C6 - Engine ECU (TACH Terminal)

MPX: Muliplex communication.

Connector A has 22 pins, B 18, and C 10.

DAZ400 · April 10, 2004, 10:31

Martin is right there is a micro in the display and this does all the local display functions.

The Signals marked.

B4 - Engine ECU (MPX2 Terminal)

C5 - Engine ECU (MPX1 Terminal)

Are I belive the differential CAN BUS signals and these are used to communicate with the engine ECU supplying all the relavent Data.

There is also a CAN BUS interface on the SMT Bosch ECU which connects to the Engine ECU and the gear shif data is passed this way.

Hope this helps

Darren. s:D

s:D

crankshaft · April 23, 2004, 05:19

Hi Darren;

Has anyone cracked the protocol ?? - do you know what baud & number of data, start & stop bits etc ?? I want to intercept the data packets and feed them into a micro to provide an alternative high-intensity gear selector display, probably with an auto-dim and maybe even a voice prompt of the gear upon change, but that may be annoying !.

With the roof down and the sun shining, I can't see the LCD display, and with the SMT I am constantlly looking to see what gear I am in.

I've also thought about replacing the rev counter with a colour LCD display providing a rev counter, batt voltage indicator, oil pressure, water temp, remaining milage (based on average fuel consumption), as well as other engine data which may be available !. I've also thought about some kind of graphic display which is mapped to the power curve of the engine and displays a coloured rev-counter or 'remaining power' which changes colour with the engine power.

I guess what I really need is an old dashboard and the ECU it talks to (hopefully it's just the one ECU)

Crankshaft.

crankshaft · April 23, 2004, 10:56

Hmmm, I have done some research. Toyota has developed the BEAN intrerface (Body Electronics Area Network) which runs at 10kb/s, uses a single wire with a header length of 25 bits and data length of 1 - 11 Bytes, so I'm not sure if this uses differential comms.

I don't have the wiring diagram, but as the inputs which you all reported to me are identified as MPX1 and MPX2 and not marked BEAN Bus or something similar, I believe that this may not be the BEAN bus, but maybe just a simple multiplexed signal comprising of possibly 1) Rpm, 2) Mph, 3) Temp, 4) Fuel, 5) Gear Number 6) Warning Lights etc ??

Does that sound logical ?? - can someone scan or fax me a copy of the wiring diagram showing the ECUs, Dashboard and the BEAN Bus connections between them ??

Cheers

Crankshaft

DAZ400 · April 23, 2004, 11:45

not sure about the bean bus part from the SMT ECU because it is BOSCH I am pretty sure this is CAN bus.

I know that the OBDII is a 10KHz single com line that is bi-directional.

I can't help any more at the moment as I am packiing to move..... s:wink: :wink: s:wink:

crankshaft · April 23, 2004, 12:29

Hi;

OK, hope the move goes smoothly !

I may take another route which is OBD II, does anyone know which type of OBD II connector the 2 has, type A or Type B and where exactly it's located ??

m http://www.scantool.net/support/?_a=kno ... tails&_i=3 m

Type A = Single Centre Slot, Type B = 2 Centre Slots

Anonymous · April 23, 2004, 12:33

Type A and it's under the dash on the drivers side.

crankshaft · April 23, 2004, 14:49

Cheers, I have seen some previous posts (spyderchat, MR2ROC) that state that pin #5 is missing (Signal Ground), and that OBD II won't work on the 2, but pin #4 is there (chassis ground). I am a long way from my 2 so can someone see if there is a contact in pin position #5 (top row, 5th from the left) ??

There are quite a lot of OBD II > RS232 interfaces around (datalogger etc), but I intend to do away with a PC / Notebook and provide this info on a 'cool' colour 4" x 4" Colour LCD Panel without any PC/Notebook.

Crankshaft

Anonymous · April 23, 2004, 16:27

OBD2 won't work on the Jspec only. It's ok if you have a UK car.

I tried feeding a ground to the pin5 that is missing but the reader still didn't work. So back to the drawing board for me.

crankshaft · April 23, 2004, 16:49

Hi, let's try and solve this. U have a OBD II decoder ?? - I am looking at the wiring diagram for the OBD II and it states that pin 4 is chassis ground and pin 5 is logic ground.

How did you feed ground to this pin ??

Crankshaft

DAZ400 · April 23, 2004, 18:14

It was my OBDII interface the scantool one and I checked the connections and chassis GND is not connected to the interface with the cable so I shorted the 2 pins on the interface board so signal and chassis would be connected together effectivley. The software and interface tried to communicate and recieved some data but kept getting comms errors, it is basically very similar on j spec cars but is not the same as uk, with some knoledge of the protocol it could be done basically the chip in the scantool is like a pic with a standard uart and some io pins to do 10KHz interface with the car. s:wink: :wink: s:wink:

Anonymous · April 23, 2004, 18:19

Quote from: "DAZ400"It was my OBDII interface the scantool one and I checked the connections and chassis GND is not connected to the interface with the cable so I shorted the 2 pins on the interface board so signal and chassis would be connected together effectivley. The software and interface tried to communicate and recieved some data but kept getting comms errors, it is basically very similar on j spec cars but is not the same as uk, with some knoledge of the protocol it could be done basically the chip in the scantool is like a pic with a standard uart and some io pins to do 10KHz interface with the car. s:wink: :wink: s:wink:

Er, yes, that's just what i was going to say s:? :? s:? s:oops: :oops: s:oops:

crankshaft · April 25, 2004, 12:00

Hmm, Page 7 show a diagram which indicates that pins 4 & 5 are linked and connected to the chassis ?? - but I guess that that may not be the case for all toyota models.

m http://www.autoshop101.com/forms/h47.pdf m

As Mr-s_turbo mentioned, Is it confirmed that only the Jspec cars that have a problem using scan tool with OBD II ??

Cheers

Crankshaft.