removing and reinstalling the diagnostic port in RWD project

peregrine · 12-31-2004, 02:27 AM

whats entailed in this chore? it looks pretty hairy from what ive looked at so far. basically ive got everything i need for my RWD swap but i will need the diagnostic port for tuning purposes. how is it hooked to the ecu? is there a simple harness? would i even need it if i buy the 1g dsmlink? thanks in advance.

steve · 12-31-2004, 03:06 AM

It's trivial compared to the rest of the wiring you have in front of you.

The 1G ECU uses three wires for communicating with a datalogger.
Pin 1 on the ECU is the data line and runs to pin 1 on the DLC.
Pin 2 on the ECU is the mode select and runs to pin 10 on the DLC. Grounding this puts the ECU in diag mode where you can talk to it.
Pin 12 on the DLC runs to ground and is the return path for the signal on pin 1.

Steve

4g63mightymax · 12-31-2004, 06:17 AM

I have done a 4g63 RWD project and the wiring is by far the toughest part of the entire project. The best advice I can give you is to start off with a running car/engine, and swap EVERYTHING including the whole harness. Get the vehicle running, and then start removing stuff you dont need. I started with a bent valve engine from the junkyard and no harness. It took me forever to get it running correctly because there were so many different factors to look at. (Not to mention 1 million wires that had just been swapped over) I had the engine and trans in and mounted correctly in about a day and a half. Making the engine run correctly took months (although I could only work on it 1 day a week)
To answer your question. If you can figure out the rest of the wires, the diagnostic port is very easy. Just follow the wiring diagrams.

Jeremy

peregrine · 12-31-2004, 01:10 PM

well all the parts im using minust the motor came off of two parts cars so iii dont have anything running. i have the complete harness for the fuel injection etc. so that will be easier. i knew the wiring would be tough but will be well worth it in the end. thanks for the input.

peregrine · 12-31-2004, 08:26 PM

heres another question. i figure i dont really *need* the diagnostic port if i tune it with a wideband. can the ecu run with a dsmlink without the diagnostic port?

steve · 12-31-2004, 08:39 PM

I haven't seen a 1G link yet but I assume it uses the DLC to talk to the ECU, if so how would you tune with your wideband if you can't hook up the link to the ECU.

I guess I'm missing the point. It's only 3 wires, what's the problem?

Steve

peregrine · 12-31-2004, 09:32 PM

Quote:

Originally Posted by steve

I haven't seen a 1G link yet but I assume it uses the DLC to talk to the ECU, if so how would you tune with your wideband if you can't hook up the link to the ECU.

I guess I'm missing the point. It's only 3 wires, what's the problem?

Steve

i think i misunderstood your first post. it actually seems pretty simple after looking at a wiring diagram in the chilton manual.

steve · 12-31-2004, 09:51 PM

Quote:

Originally Posted by peregrine

it actually seems pretty simple after looking at a wiring diagram in the chilton manual.

Exactly. It shouldn't take you very long to do this.

Steve

peregrine · 01-03-2005, 07:46 PM

just to put some closure to this thread for future searches i am sending the harness and port to eric plebani so he can shorten and eliminate everything unneeded. well worth the money IMHO.

DJpHGotBanned · 03-09-2005, 08:20 PM

If anyone ever needs help with DSM engine wiring for odd swaps, I'd love to help.

Wiring this motor is EXTREMELY simple. Alot of you seem pretty intimidated by it. The key is NOT to swap the whole chassis harness. Many people who have tried the swaps have this bizarre idea to swap it all over only to get frustrated, sending it off or starting over.. and basically wasting their time and money. For what really? You can get most every option of the chassis to work independently of the motor harness.

Every EMS (stock or standalone) needs the same basic inputs and outputs. You only need to concern yourself with a few electronic gauges, Const 12V, Keyed 12V, IGN and ST and in you case the OBD plug wires (2 really.. plus ground).

Once you get a handle of DC wiring, it opens up some awesome opportunities. You can strip the stock harness down to the minimum in about an hour and race cars with no more than 8 wires in the entire chassis take a few hours.

Now a new Corvette! Now that's some crazy stuff.