cartmill

iTrader: (3)

ok guys, so i made the big thread about the 5 speed swap in the 98+, figured out that you can just plug in all your solenoids/valves and use resistors to get the CEL off for the missing transmission.

well, now i'm battling the P1780 CEL code, which is just the "Park/Neutral position switch." this is the switch that is down at the transmission end of the automatic shifter.

anyone feel free to check out these attachments and offer any ideas of how to get this code to go away. i'm starting to get confused.

scENFORCER

I assuming another resistor wont work? So the CEL is there when you're not in gear?

Btw is this for a 300 or 400? I've always wanted to do this to my '99 400.

BartleDoo

iTrader: (1)

You might just need to close that circuit since it is open now that you pulled the auto shifter out right?

Klaus

iTrader: (1)

Why? You already have a 5 speed

cartmill

iTrader: (3)

this thread is becoming a failure.

stockhatch, where are you man.

cartmill

iTrader: (3)

okay, i have been leaving my park/neutral switch jumpered, which will make the code pop up the next day.
i thought was causing the CEL, BUT when i only jumper it to start the car and then remove the jumper totally (supposedly making the ECU think it's in "D") the P1780 code shows up as soon as i hit 44mph.
this is what's confusing me.

Klaus

iTrader: (1)

Can't you just ground out D?

stockhatch

iTrader: (12)

So you are opening up the switch completely, and relying on the "If no signal is detected, the ecu behaves as if the car is in D" statement that you read in the manual?

Or are you using the e-brake relay setup still to actually jumper "D" when the e-brake is down?

If you are doing the first thing, I would do what Klaus said, and make sure you are physically jumping "D" when you are not starting the car.

Is there an OD on/off switch on the late model cars? If so, is it on, off, or missing?

These fancy pants OBDII ecus are really smart man. Maybe too smart for their own good. It is possible that it runs some test routine at speed and doesn't like a solenoid voltage or resistance, or some lack of tranny input of who knows what type...?

I know Dr Tweak tried to develop a tranny simulator for the OBDII cars, and it still has not successfully worked AFAIK.

Not trying to rain on your parade or anything, but you may be out of luck bro. There is only so much caveman foolin' you can do to the OBDII cars. That's why I am glad I have a "stupid" OBDI car. You can omit half its signals and it purrs happily along

cartmill

iTrader: (3)

i have left P and NSW jumpered, went for a drive, CEL comes on when i turn the car off and back on.
i have left N and NSW jumpered, went for a drive, CEL comes on when i turn the car off and back on.
i have left P and NSW jumpered, removed jumper, jumpered D, went for a drive, CEL comes on when i turn the car off and back on.
i have jumpered NSW only, went for a drive, CEL comes on when i turn the car off and back on.
i am super confused.
i'm doing nothing of the P1780 "flags" listed in that last picture i posted...

stockhatch

iTrader: (12)

Did you check for voltage on the NSW pin of the ecu when the ignition is on and the car should think its in "D"?

Apparently, the car still thinks it is in "N" for some reason even when you remove the jumper. I wonder if the PO may have done some wiring between the ECU and the trans switch that would give the ECU pin NSW a constant hot?

Jump "D", leave everything else open, and check pin NSW for 12v at the ecu with the key on. If it is hot, you know where to look for your problem.

BartleDoo

iTrader: (1)

Do you have the pinout diagram for the ecu by chance?

cartmill

iTrader: (3)

i figured it out.

the relay i had hooked up (put the ecu in PARK when the ebrake is up, DRIVE when the ebrake is down) had Drive as the normally closed pin on the relay. i was disconnecting power to the relay and wondering why it was still thinking it was in neutral and drive at the same time, but it was because the DRIVE was connected whether or not the relay was powered...

the interesting thing, though, is that i have to leave the NSW jumpered 24/7 to keep the CEL off... if i jumper it only to start the car, then disconnect it, it will throw the CEL on as soon as i get to 40mph...

anyways, i'm leaving the NSW jumpered, and the CEL is gone

stockhatch

iTrader: (12)

Oh, cool deal. That is weird though about NSW having to be jumped all the time.

cartmill

iTrader: (3)

yeah i was planning to actually wire in the NSW on the clutch pedal, but oh well.

scfou

iTrader: (3)

Cartmill, will you pass smog in that case?