P59 in gear vs park/neutral determination?

[DSteck]

On the P59, does the PCM determine the status of in gear vs park/neutral based on the PNP signal from the PIM, or does it use PRNDL status?

I'm dealing with a swapped vehicle running a 2004 GTO harness and PCM. There's no PNP switch wired up, and the PRNDL Status always says D4. I'm pretty sure the starter doesn't get permission from the PCM either. The problem I am having is when shifting from park or neutral to reverse or drive, the IAC doesn't instantly adjust and the engine bogs. Sometimes it will die. Normally, you can see the desired idle airflow jump immediately when shifting into gear. On this vehicle, desired idle air only goes up when the idle speed tanks until it finally adjusts up to desired. If you shift back into neutral, it slowly drops the idle air by 0.4 lb/min instead of instantly.

If a PIM is required to tell the PCM the difference, then I might be better off switching this thing to a F-body PCM since those use a direct signal to the PCM for park/neutral. If PRNDL status is the determination, we can just wire up a PNP switch. I just don't want to waste time doing one or the other.

[LSxpwrdZ]

Pretty sure PRNDL... range selection switch is

Blue 32 = Trans. Range Switch Signal "A"
Blue 72 = Trans. Range Switch Signal "B"
Green 62 = Trans. Range Switch Signal "C"

I'm guessing also a GTO OS?

[CalEditor@pcmcalibrators]

In the system segment the calibration has a couple of setting that need to be set correctly.

I have stopped using the GTO calibrations. They run the same OS as other 2004 vehicles and it's not a big deal to setup a DBW calibration as a DBC. I am in the process of building a calibration series for this type of swap.

contact me if you would like a calibration

[DSteck]

I have access to the GM service site, so I had pulled the wiring diagram for the PNP switch as well as the switch logic. You're missing the P switch though. We were going to ground specific wires to check for changes in the PRNDL status (currently stuck at D4) as well as look to see if desired airflow changes.

The swap is all done and fine. I just need to get a gear signal to the PCM. It's a 2004 A4 GTO setup in a 94 Impala SS with a cam and Edelbrock E-Force. Literally the only problem I have is the damn garage shift. I'd love to switch this thing to a 0411 since I'll get better resolution in the VE table as well as a simpler architecture that will work better for the application. Can you verify that the stock 04 GTO operating system uses the PNP switch outputs to determine the status? I can't imagine they'd rely on the PIM for that info just in the event of a serial communication error.

Thank you both for your replies.

Hey Chris... The switches might be nice to have.

[CalEditor@pcmcalibrators]

The 2004 GTO OS 12587604, but I have a few that are 603's if I remember correctly.
2004 -- Truck & GTO -- 12587603
2004 -- Truck & Vette -- 12585950
2004 -- GTO -- 12587604
2004 -- CTS-V -- 12588804
2004 -- Vette LS1 -- 12592425
2004 -- Truck Flex -- 12606960
2004 -- 8.1 -- 12612114
2004 -- Holden & CTS-V -- 12592433

[DSteck]

I've got a custom OS in this one for 2 bar, but I'll check the base OS when I get home.

[CalEditor@pcmcalibrators]

Year -- Model -- GM OSID -- PCM ID -- 1 Bar Map SD -- 2 Bar Map SD -- 3 Bar Map SD -- 1 Bar MAF Enhanced
2004 - GTO --- 12587604 --- P59 ------- 1271053 ------- 1251053 -------- 1260053 ------- 1281053

I have almost every custom OS mapped to the original OS, but if I post the document the moderators pull it.

[DSteck]

12587604 was the original OS.

I see an option to choose if it's P-N only or PRNDL equipped (it is set to PRNDL). Is this what determines where it gets the in gear vs neutral decision?

[CalEditor@pcmcalibrators]

P/N is like an F-body with the switch on the shifter
PRNDL is for a truck and Vette
None is for a Manual or a big truck with a TCM (Top kick)

[Bluecat]

On Gen3 pcms just set it to "none" and it gets its data from the pressure pad array in a 60 or 80 to determine gear or P/N. Its how F-bodies are factory.

[DSteck]

On Gen3 pcms just set it to "none" and it gets its data from the pressure pad array in a 60 or 80 to determine gear or P/N. Its how F-bodies are factory.

You are a sexy beast. That did it!