Need Help from Electrical Gurus

[SmokingRocks]

Thanks for all the help @landcrshr

 

[landcrshr]

Thanks, that helps.

It looks to me though that the transistor you pulled from the board is actually the voltage regulator transistor. Sorry.

As far as the conditioning circuit, that appears to be the inline IC at the bottom, along with several other surface-mount components that are impossible to identify. Sorry again.

It will be possible to make your own IC signal conditioner, but it's going to take some significant R&D. I guess your other option would be to put the speedo board back together and piggyback it in the system.

 

[SmokingRocks]

Damn. thanks for the input though.

So when I first made my cluster I tried to piggy back the speedo board remotely and it didn't work. But I also may have broke the board (it cracked and I tried to solder over the cracks to re-establish the pathways).

I guess you're right thats probably my best bet. I'm still perplexed though since the CCU worked with just a resistor between the VSS and its signal input, yet now it doesn't work but the ECU/TCU both see the signal with the zener in. Perhaps I just need to reinstall the transistor, resistor and then test it. I do have another 80 sitting here that I could borrow from.

 

[SmokingRocks]

OK I spent about 2 hours with a multi meter checking continuity and resistance across the board. I think I've come up with a map that may accomplish the goal. Can you please check it over @landcrshr ?

I don't know what either of these components are, the first one on has no voltage or resistance across it. The blue component has 2.2mV across it when 12 volts are applied to the side with the blue mark on it.

I couldn't identify the direction of this zener, it doesn't register on my multi-meter when its in diode mode. With voltage applied the output is in 23.4 ish mV.

 

[sbman]

The first item looks like either a coil or a ferrite bead. Often ferrite beads are used to kill noise coming in, or going out from the external circuitry.

The blue one looks like a capacitor to me. I believe it's a polypropylene 0.22f uF, good for 50V or so.

The 'ZNR' device looks is a varistor/surge suppressor, also part of protection from the outside world. Technically, a varistor. It's a Matsushita ZNR series:
Matsushita ZNR-20K431U Varistor Surge Absorber ZNR20K431U - New No Box - Mara Industrial

The part of your schematic where you have 'ic with continuity to ground' marked, what do you mean exactly, can you depict the IC as part of the schematic as well? It may have continuity to ground, but I don't think it's equivalent to ground, if it was, the transistor would be shorting directly to ground when it was turned on, so the I.C. is doing something as well.

Do you have O-Scope captures of what the input and output signals should look like? If not, which ones can you get?

Scott

 

[sbman]

Also, because of the crystal in the circuit attached to the Toshiba I.C. I'm thinking this is a low end Microcontroller, maybe a 4 bit device. Toyota seemed to use a lot of the toshiba parts.

 

[landcrshr]

Don't build that circuit! What you did was scavenge parts from the voltage regulator circuit and re-aranged them in an unholy manner.

Sorry, I wish I had time today to be of more help. Maybe tonight.

 

[SmokingRocks]

Thanks for your feedback @sbman

I don't have an O scope, wish I did. I'm looking at making a module so I can use my computer as an Oscilloscope.

Here are the chips

Single Row 9 pin Toshiba, 9415k, TD6905S pins labled as follows:

1. - Tach signal out
2. - this seems to go no where
3. - Signal from VSS, passes through the chip #2's pin #1
4. - no path
5. - Groung (-)
6. - Path to Odometer / Trip
7. - Path to Odometer / Trip
8. - Path to Odometer / Trip
9. - Path to Odometer / Trip

Dual Row (8 pins per row) Toshiba, TB9213P, 9417k pins labled as follows:

1. Signal from VSS to pin 3 of chip #1
2. Path to Speedometer device
3. Path to Speedometer device
   
4. Path to Speedometer device
   
5. Path to Speedometer device
   
6. Ground (-) also connects to pins 9, 10, 12, 13,14
7. To Pin #3 of chip #1 (this has the most complicated circuit on the board with tons of surface mount components.)
8. To Pin 11 (also has a bridge to ground but no continuity across it)
9. Ground (-) from pin 6
10. Ground (-) from pin 6
    
11. To pin 8
12. Ground (-) from pin 6
    
13. Ground (-) from pin 6
    
14. Ground (-) from pin 6
    
15. To Crystal
16. To Crystal

 

[SmokingRocks]

Don't build that circuit! What you did was scavenge parts from the voltage regulator circuit and re-aranged them in an unholy manner.

Sorry, I wish I had time today to be of more help. Maybe tonight.

Hahaha oh god that bad huh? I didn't think I was rearranging anything just perhpas cutting out the chips that controlled the needle and the odometer. Either way I'm glad you here for me! I'm literally learning about all of this as I go, I'm a beginner when it comes to electronics.

 

[retrofive]

I'm horrible at electronics, so this is a little fascinating and intriguing to read and watch the progress. I would say if I had half the knowledge of you guys attempting this I would all over an O-scope. Looks like you can buy some decent ones for $200-300.

 

[SmokingRocks]

I spent 10 bucks on a circuit simulator.. Ya I guess my latest drawing wont work.

Oh well, I'm going back to this layout:


Since the sensor is a Hall effect type the signal output is already square. So I just need to get the voltage right.

 

[landcrshr]

I don't think you need to worry about getting the voltage right.

I suspected earlier that the voltage was "pulled up" by the ECU and this confirms that:

That diode on the input also isolates it from any outside voltage.

So the speed signal's job is to pull the ECU's input to ground. It doesn't provide any positive voltage.
I'll try to come up with a circuit for you.

FWIW, this looks like the transistor responsible for the speed signal:

 

[SmokingRocks]

Thanks that diagram is very helpful is that out of the EWD supplement FSM?

Can you post the cruise control computer??

 

[SmokingRocks]

And are you looking at the OBD2 ECU? because from what I found in the attached files is that the OBD 1 system is looking for 5 volts not 12 like the OBD 2 system.

Again keep in mind that the ECU is seeing the speed signal from the VSS with my simple zener 5v cap circuit running. I just checked for codes again and there are none. Which makes sense because its still sending out a pulse 5v

The issue is the cruise control is not able to see the speed sensor. I think the addition of the transistor will provide the ground it needs to work. I'll give it a shot.

 

[bloc]

You guys are way above my head in most of this but I can say that a 97 cruise computer will work with the output signal from a 94 speedo. That is the setup I was running after my body swap.

 

[landcrshr]

the OBD 1 system is looking for 5 volts not 12 like the OBD 2 system.

What I'm saying is that the ECU isn't looking for ANY voltage. It PROVIDES the voltage.

Please try to comprehend this:

That diode on the input also isolates it from any outside voltage.

So the speed signal's job is to pull the ECU's input to ground. It doesn't provide any positive voltage.

And that is how @bloc was able to mix compents from different years. (Thanks bloc, that's helpful to know).

 

[SmokingRocks]

I comprehend that. And I did then too, sorry I worded the response wrong its been a long day of this.

What about the Cruise Control? Thats the main question.

 

[landcrshr]

Same goes for CC ECU. Voltage is pulled up internally and isolated from outside voltage.

 

[SmokingRocks]

Thanks everyone for the advice and help, particularly @landcrshr for sticking with me through this. I think I've got it figured out now.

This is the circuit when the VSS is sending signal.

Then when there is no signal the current flows backwards and through the Emitter of the combination unit.

I realize the voltage in the computers is 5 volts not 12, 12 just made the circuit light up more clearly.

So I just need to install a transistor with a resistor on the Collector side and ground the emitter then tie it into the VSS and SPD signal line.

Wish me luck.

 

[sbman]

@landcrshr has a point, the voltage is supplied by the cruise control ECU. YOur circuit from the simulator is close. You want to hook up the Cruise Control ECU to the location you have +12V, and drop the 100K resistor you don't need it. The 7K may not be necessary either. You just need to switch the cruise control ECU speed line to ground with the speed signal, and it has resistors inline aready. A standard NPN transistor should get the job done. I don't think you need the zener either. It won't be as electrically robust as the OEM circuit, but it will probably get the job done.