Input pins available for reuse on an 0411 in a manual trans F-body

[JakeRobb]

'02 Z28 M6, 0411 PCM.

I know that the EGR circuit is unused on '01-02 F-bodies and '01-03 Corvettes. I'm planning on using that for my wideband. But there are a few other things I'd like to add (oil temp, fuel pressure, ambient temp) and be able to datalog.

Are there other inputs on my PCM which are unused? I was thinking in particular that there might be something that's there for use with automatic transmissions, which would be unused on my M6 car. Perhaps a trans temp or pressure sensor? I'm not sure what's there; automatics aren't really my area.

If there are such circuits, can anyone tell me the pin numbers? Would I need to do anything special (e.g. load a different OS) to make these circuits active and available in my PCM?

[JakeRobb]

Found this thread at PCMHacking.net, which discusses 0411 pinouts, but is not F-body specific.

These two were consistent across both platforms shown in that thread:
PIN 17 - Dark Blue - Circuit #1225 - Transmission Fluid Pressure Switch Signal B
PIN 18 - Red - Circuit #1226 - Transmission Fluid Pressure Switch Signal C

And then some others, for which the pin numbers and other details differ by platform:
Transmission Temperature Sensor Signal
Transmission Range Switch Signal A
Transmission Range Switch Signal B
Transmission Range Switch Signal P
Damping Lift/Dive Signal

Would I be able to use any of these?


There are of course other trans-related things, but they seem to be outputs (solenoids). I assume output pins can't be repurposed as inputs.

[JakeRobb]

Also found this: https://lt1swap.com/99-02_vortec_pcm.htm

PRND A / B / C seem promising. I assume those are the same as the "transmission range switch signals" listed above.

[JakeRobb]

Found this in the factory service manual, showing the pinout of the automatic transmission wiring harness: Attachment 140224

Here's the engine-side of the connector:
AT harness connector.png

Pin	Wire Color	Circuit	Description
L	YEL/BLK	1227	Transmission Fluid Temperature (TFT) Sensor Signal
N	PNK	1224	TFP Switch Signal A
R	DK BLU	1225	TFP Switch Signal B
P	RED	1226	TFP Switch Signal C
M	GRY	452	Low Reference

Assuming these are viable, I'd just need the corresponding PCM pins.

[JakeRobb]

Found the equivalent diagram on the PCM side: Attachment 140226 <-- PDF with complete 2002 F-body pinout!

Red Connector:

Pin	Wire Color	Circuit	Description
63	YEL/BLK	1227	TFT Sensor Signal
51	PNK	1224	Transmission Fluid Pressure Switch Signal A

Blue Connector:

Pin	Wire Color	Circuit	Description
17	DK BLU	1225	Transmission Fluid Pressure Switch Signal B
18	RED	1226	Transmission Fluid Pressure Switch Signal C

The wire colors and circuit numbers aren't super relevant to me; I'd be using them for entirely unrelated circuits, and I don't expect the wires to even be there at all.

One thing I haven't found yet is which pins supply the ground and reference voltages for those sensors.

[JakeRobb]

And, from the 2000 Service manual, here's EGR:

Blue Connector:

Pin	Wire Color	Circuit	Description
41	BLK	407	EGR Pintle Position Sensor Ground
47	GRA	416	EGR Pintle Position Sensor 5V Reference
55	BRN	1456	EGR Pintle Position Sensor Signal

[gtstorey]

You are going to have to determine which of those are looking for a 0-5v signal or something similar vs a discrete on/off or some particular value for it to perform an action.

[JakeRobb]

Turns out the fluid pressure switches are just that -- switches. They're either on or off, and they use ignition voltage. Thinking I probably can't use those.

Also thinking TFT might not work either. From the manual:

The sensor has a negative-temperature coefficient. This means that as the temperature increases, the resistance decreases, and as the temperature decreases, the resistance increases. The powertrain control module (PCM) supplies a 5-volt reference signal to the sensor on the signal circuit and measures the voltage drop in the circuit. When the transmission fluid is cold, the sensor resistance is high and the PCM detects high signal voltage. As the fluid temperature warms to a normal operating temperature, the resistance becomes less and the signal voltage decreases.

[JakeRobb]

You are going to have to determine which of those are looking for a 0-5v signal or something similar vs a discrete on/off or some particular value for it to perform an action.

Yep, thanks -- that's what I had just figured out. The "switch" ones appear to be off the table.

[gtstorey]

If the pid will display a voltage range, it will probably work as long as you can turn off it's normal function. But does the ecm have the internal circuit to connect it up? I'm not following where all of these pinouts are being pulled from or know enough whether all 0411 are the same internally.

[TheMechanic]

Should work actually. If you use the OS from the automatic trans and then remove TM, zero out any spark changes and any sensor you use is a 0-5v range you should be able to with a "Math" get an accurate pressure output.

[JakeRobb]

If the pid will display a voltage range, it will probably work as long as you can turn off it's normal function. But does the ecm have the internal circuit to connect it up? I'm not following where all of these pinouts are being pulled from or know enough whether all 0411 are the same internally.

The pinouts are coming from the factory 2002 F-body service manual. Except for EGR; I pulled those from the 2000 manual.

[JakeRobb]

Should work actually. If you use the OS from the automatic trans and then remove TM, zero out any spark changes and any sensor you use is a 0-5v range you should be able to with a "Math" get an accurate pressure output.

Yep, that's what I had in mind, same as what people do to monitor a wideband via the EGR circuit.

It seems like I can use the transmission fluid temp (TFT) circuit, but I think that's the only additional circuit with the capabilities I need. So of the four things I'd like to add (that I've thought of so far), it looks like I will have to pick my top two. At this point I'm thinking wideband and fuel pressure. Maybe I'll set things up so that I can just quickly change some plugs under the hood and toggle the math fields in and out of the scanner layout. Once I have the tune dialed in, I won't really need the wideband as much, and I'd probably choose oil temp and fuel pressure for track day logging.

I need to check the C5 service manual and see if that lists any additional viable circuits. Maybe I don't have to choose!