gjohnson

iTrader: (4)

Ok, I'm looking for a little insight on the GTO PCM and Pinout. I have a L33 with T56 that I've swapped into my 97 240sx. Initially I had a Truck PCM, DBW throttle body and truck harness, but I ran into issues with the DBW setup. I ditched the DBW and picked up a DBC throttle body. I also swapped my Truck PCM (green and blue connectors) with a 04 GTO PCM (green and blue connectors) and removed all the DBW wires/ pins from my truck harness. The swap was fairly easy and straight forward, but the only snag I've found is that the Truck PCM had a the following pin on the Blue C1

75 PNK 1020 Off/Run/Crank Voltage


It's seems just about every other wire on the 04 Truck PCM and The 04 GTO PCM line up with the correct pin.

Now the problem that I'm having is, I have wired in the TPS and IAC plugs per the GTO pinout and the car fires right up and runnings great, I have no codes or check engine light, but when I turn the ignition off the car does not shut off and the fuel pump doesn't seem to stop priming. Again I am only assuming the pin above on the Truck PCM controlled this, but if not what am I missing or is this function controlled by something else on the GTO pin. I have only started the car once since I've had this issue, but I was planning on working on the issue tonight and could use some help.

Also, the only I was able to shut the engine off before was I turn the ignition to crank again (attmpting to crind the starter) and the vehicle shut off. Not sure why.

Thanks for any help.

the_merv

iTrader: (88)

I would pin that wire into the correct spot first then check it again to see if it does it. Do that and go from there.

Pocket

iTrader: (22)

Think about it, the only time that pin DOESNT have 12v is in accessory position

Not having enough power will not cause an engine to stay running

Most likely the issue is a main IGN connection was hooked to a constant 12v source. Check for 12v on the injector and fuel pump relay pins with the key off

gjohnson

iTrader: (4)

Ok, I would take a look at that. 1 thing that I just thought of was checking my fuse box to make sure that I don't have any orange and pink wires touching or crossed. Accordingly that does bring up something strange for me.

The Truck has the following connections on C1

19 PNK 439 Ignition 1 Voltage

20 ORN 440 Battery Positive Voltage

57 ORN 440 Battery Positive Voltage


the GTO has the following

19 OG 300 Ignition 3 Voltage

20 OG 740 Battery Positive Voltage

57 OG 740 Battery Positive Voltage

So in other words, I currently have pins 20 & 57 wired constant and 19 as a pink +12v keyed wire.

Pocket

iTrader: (22)

Thats right

gjohnson

iTrader: (4)

Hmmmmm. Ok, what would cause the fuel pump to continuely prime and not shut off after 2 seconds when the key is in the ON position?

the_merv

iTrader: (88)

The Crank Sensor Signal NOT telling the PCM that it's not movin.

Pocket

iTrader: (22)

A bad crank sensor usually does a whole mess of things, but telling the PCM its running is not one of them. The crank pos sensor reads the reluctor ring as it rotates and sends a wave signal to the PCM. When the reluctor isnt rotating the signal is either full open or full closed (good and bad sensors). Again, not a wave so the PCM knows the engine is not turning

For more info on the crank sensor read this thread
http://www.thirdgen.org/techboard/lt...g-problem.html

The fuel pump relay is engaged by receiving 12v from the PCM when the IGN is on. Since it constantly receives 12v, it leads to assume the PCM is getting 12v constant at the IGN pin. Grab a multimeter or testlight and check for 12v constant on pin B19. While you're at it, go ahead and check that pins B20 and B57 are connected to the battery

gjohnson

iTrader: (4)

Well, I was talking to Poconojoe last night and that's basically what we were thinking as well. I haven't had a chance yet to get out there any try and correct the wiring yet , but I will take a look at it later tonight.
What we came up with was, currently pin 19 Ign 3 is wired in with all of the pink wires, which means it's not connected directly to the ignition wire, but a relay that is controlled by the ingintion wire. Like seen in this post.
http://www.lt1swap.com/fuseblock_3.jpg

Joe, was thinking that this would be causing the pin 19 to get a constant 12v signal when the relay is activated.

Wing Zero

The problem is the truck wiring and GTO wiring are not the same. It is not in the power side but the sensor wirng. Find the computer pin out of truck and GTO and u will see were.

Pocket

iTrader: (22)

Thats still backwards logic. NOT having 12v somewhere will not lead to a no shut down situation. I will lead to a no start

A faulty sensor circuit will result in a sensor not functioning. They prevent starting, but they will never prevent a shut down

Doubledip

with ign off and pcm plug disconnected have you measure pin 19 to see if there is any power there.. did you make this fuse box setup like in the picture...? have seen fuse boxes like shown where one side has al the pins connected (normally you connect one bat power in) then all the other sides are seperate to goto different circuits.

gjohnson

iTrader: (4)

I have not checked the power to PIN 19 with the PCM unplugged, but I did pull out he multimeter last night and I checked PIN 19 while connected to the iginition relay. Currently with the PCM connected and the ignition off, pin 19 has no power, when you turn the ignition to on or crank, pin 19 gets full voltage. If you turn the ignition back off without starting the car, pin 19 no longer gets power, but if you start the car pin 19 gets full power no matter if the ignition is turn off or not. I have also found that to turn the car off when the igition will not, all you must do is remove PIN 19 from it's power source.

Also, the fuel pump will prime when the ignition is turned on or to crank, regardless whether the fuel pump relay control from the PCM is connected or not. So, I'm starting to think my relays are wired wrong or something, but I don't understand why they worked fine with the Truck PCM, when the only diff I can find is PIN 19.

Pocket

iTrader: (22)

Sounds like a bad IGN switch

gjohnson

iTrader: (4)

Hmm.... maybe the ign switch is bad, but I was thinking it may have more to do with the GTO starting system. Does anyone happen to have any notes on how they wired up the their starting system with this GTO PCM. I think that maybe I may have to add or remove a relay and modify my starting system. Any ideas?

gjohnson

iTrader: (4)

Well, I did just find this little tid bit while searching on google. It may explain why my fuel pump never shuts off, but I don't know how I would fix it.

But I do have the Helms for 04 GTO open on my desk, the following is more or less verbatim...

page 6-678: When the ignition switch is on, the PCM activates the in tank fuel pump. The fuel pump remains on as long as the PCM receives the reference pulses from the ignition system. If no pulses, the PCM turns the fuel pump off after 2-3 seconds. The rpessure regulator, located in the fuel tank maintains system pressure at 55-60psi, excess fuel returns to the tank.

71 chevy

iTrader: (18)

could your alternator be backfeeding the ignition somehow? I know this is possible when not using a factory harness but I dont know if its possible with the factory harness

Pocket

iTrader: (22)

Technical speak for it stays on during the IGN power being supplied to the PCM and is shut off when IGN is removed

Test this theory, run a new wire to B19 with a fuse and a common toggle switch. If it runs like normal, replace the IGN switch. It needs to only send 12v when its supposed to. If it gives 12v in the off position you will never get reliable service from it

r7moffat

Pull the two wire connector on the alternator, and re-start the vehicle, does it now turn off with the key? If so, you need a diode in the wire that connects to the alt light. Feedback from the alt is causing your relays to stay engaged and keeps in the engine and pump running.

Pocket

iTrader: (22)

Two problems with that

1) Alt output is directly to the battery and hooked to 12v constant. Shutting the alt down will not remove power from the 12v switched pins

2) The alt is wired directly to the PCM, no bulbs or diodes in between unless it is retrofitted for a carb application which he is not. A bad alt with usually not charge the battery enough, and in very rare cases, completely drain it. Neither apply to this situation