Gearshift Maps

[longassname]

soooo

degrees c = .5882 (atft value) -40

?

[longassname]

20c=68f=3 to 3.5v
80c=176f=1 to 1.3v
(note 2 volts change = 60c = 1 volt per 30c in normal operating range of sensor, theoretical range then is 0 to 150c)

or using the middle of the voltage ranges given for the temps in the fsm:

20c=3.25v -->(3.25/5*255=166=a6) --> (ones complement of a6)5a=90
80c=1.15v -->(1.15/5*255=59=3b) --> (ones complement of 3b)c4=196

(80-20)=m(196-90) m=.566

80=.566(196)+b b=-31
20=.566(90)+b b=-31

y=.566x-b
degrees c = .566(atft value) -31

[longassname]

I'll eavesdrop on the select monitor to get some values to double check/refine the equation.

for now it's looking like I'll try something like
c024:e7
c025:df

expecting the warning light to come on at 100c=212f and go off at 95c=203f

[b3lha]

Originally Posted by longassname

degrees c = .566(atft value) -31

That's why I was thinking Fahrenheit.

C=0.556F-32

Actually, I was surprised that the TCU doesn't use a graph to map sensor voltage to temperature like the ECU does. If it's anything like the ECU, it may not be linear at the top and bottom of the scale.

Have you ever tried reverse engineering the Select Monitor itself?

[longassname]

I just emailed you the bins.

[longassname]

I think celcius = .556 (farenheit-32)

Originally Posted by b3lha

That's why I was thinking Fahrenheit.

C=0.556F-32

Actually, I was surprised that the TCU doesn't use a graph to map sensor voltage to temperature like the ECU does. If it's anything like the ECU, it may not be linear at the top and bottom of the scale.

Have you ever tried reverse engineering the Select Monitor itself?

[b3lha]

Originally Posted by longassname

I think celcius = .556 (farenheit-32)

Yeah. You're right. My mistake.

[longassname]

I've gone with setting
c025 and e201 to df
and
c024 and e208 to e7

[longassname]

looks like the equation from using the middle of the voltage ranges given in the fsm is exactly correct.

I set c024 to 82 and c025 to 65 (110F) --> warning light came on at 111F

since the bit is set to turn the warning light on after failing a branch if lower or the same 111f is exactly right.

[b3lha]

Originally Posted by longassname

looks like the equation from using the middle of the voltage ranges given in the fsm is exactly correct.

I set c024 to 82 and c025 to 65 (110F) --> warning light came on at 111F

since the bit is set to turn the warning light on after failing a branch if lower or the same 111f is exactly right.

How about this for a nice simple formula:

Degrees F = value - 20

[b3lha]

Originally Posted by longassname

I just emailed you the bins.

Thanks. Very Interesting. I already disassembled the 92 bin. Any idea what cpu? The 68HC11 seems to be about 99.9% perfect, but the ROM has a few opcodes in the extension table (0x18 prefix) that aren't in the datasheet. Doesn't matter too much, I have enough good code to follow.

[longassname]

it's a hitachi 630x: hd63b03yp

clocked by a 4000 xtal

it uses a toshiba tc74hc125 for the signal from the ecu by the way (clamped before the 125)

[longassname]

Actually the tx from the ecu is pulled high and clipped not clamped and the rx line is clipped on both sides then they go through the 74hc125 to pins 12 and 13 on the 6303

I made a schematic to duplicate the select monitor interface for an interface to a ftdi ttl232r cable: http://www.ecutune.com/posts/ttl232r-selectmonitor.pdf

[longassname]

also, although it is not used I think that wire from the ecu select monitor port that nobody knows what it is is either vcc from the ecu or a comparitor input for the rxd. It is routed straight through the select monitor to pin 35 of the cartridge. In the 92 select monitor cartridge that pin traces to a dead end at a through hole for a resistor. If the resistor was installed it would connect to vcc. I suspect it is vcc from the ecu.

[b3lha]

The select monitor rom is a gold mine of information.

As expected, it has the commands for querying ecu, tcu, a/c, cruise and 4ws. Plus a full list of the parameter addresses and trouble codes. I'll document it all when I get a bit further.

I've been looking at the routines that validate the TCU romid. It supports THREE types of TCU:

7054xx: ACT4 (USDM).
7055xx: WTF???
7056xx: VTD (JDM and UK).

What could the 7055xx be?