How to wire in my data link plug for scan tool

[RVChaser]

I'm looking for help please.....I have a 1994 Firebird 3.4L that we are racing in a novice class on an oval track. The car needs to remain virtually stock. My problem is the car was completely rewired and I'm reinstalling the diagnostic plug for the scan tool. My PCM is #16184737 - from a PCM diagram that I do have which I believe is from a V8 Camaro (see link - http://www.v6f-body.com/showthread.php?t=689 ) Someone told me that I only need 2 wires - "A" and "M" of the diagnostic plug? I've done that but still have no communication between the scanner and the computer. I have direct leads running to the PCM - "A" going to "B16 & B32" ECM ground and "M" going to "B19" Serial Data. Also from that diagram on the link, I don't have an "F" lead from the diagnostic plug but one coming from the pin below which I think is "G" (black/white) which I have no idea where it is supposed to terminate. There is supposed to be a diagnostic enable wire on the PCM on a diagram I have that says its on C9 but I have no wire on this pin on my PCM #16184737. So in a nutshell - how do I rewire in my data link plug - like I said it's a race car with with only the components necessary to run.

Thanks

RVChaser

[bszopi]

Does the PCM have a removable chip in it? I'm not familiar with that PN for the PCM, but my honest guess is that it may not be compatible with your scan tool, even though you may have it hooked up correctly. What type of scan tool are you using, including the model number?

Oh, and welcome to the site.

[86FieroSEv6]

Does this help? And sometimes the scan tool will attempting to use ALCL term. B which is not used on that model.

[RVChaser]

Thanks for the welcome.....I don't have much engine experience mostly chassis set up and can wire most things - My Scan Tool is a Snap On MTS 2500 - NO removable chip

[86FieroSEv6]

Yeah. I've got the MT2500 (also affectionately known as "the brick") and the MODIS. Sometimes we cheat and move the "M" terminal to the "B" position so the scanner will pick up on it. Alternatively you can use the multi-1 connector and the hook up guide to get proper connections for communication. I've seen a lot of people go crazy because they couldn't establish a connection with certain Snap-Off (Oooops, did I just say that? hehehehehe) equipment. Check it out and let us know.

[RVChaser]

Thanks a million......I'll give it a try this weekend and let you know! Thanks again!

[RVChaser]

I spliced the M & B leads together but still have no communication. I noticed on this scanner that unless I continually hold down on the power/on button it will shut off. The mechanic I borrowed the scanner from said I don't have 12v at my data link plug to keep the scanner powered up. I've attached a diagram of a data link plug I have (it matches mine except for pin "F" - I don't have anything wired to "F" but have a wire directly below it which I didn't see marked - would it be "G"? Anyway I only have "A" and "M" wired to the computer. I have also tried adding "M" where "B" and supplying 12v to what I think is "G" - still no communication - I only have 4 leads coming from my Data link plug. Do they all need to be connected? Like I said I'm new to this.......Thanks

[86FieroSEv6]

ALDL term. G is usually for ABS diagnostic as I recall. In any case, To power up the unit you would need the power adapter cord. It would have an accessory plug to plug into the cigarette lighter and the other end plugs into the ALDL adapter on the side. If the cigarette lighter is inoperative, there is supposed to be an adapter cable that has battery terminal clips on it for the power cord. You can probably find one at Radio Shack if your buddy lost his. Wire up according to your schematic, all the way for your application. Then get the scanner powered up and we'll take it from the top.

[RVChaser]

It's a race car....no cig lighter, ABS, most everything has been removed for racing. If I hold down the power button the scanner will stay on. I currently have my data link plug wired per the schematic - "A" to the ECM ground pin "B16 & 32" and "M" to serial data "B19" - hold down the power button, put in the car's information select read codes and the scanner says no communication. Also wired "B" of the data link plug with the "M" lead with the same result.

[86FieroSEv6]

I have never tried to use the battery button to establish communication. For the V6 running a V6 ROM, to my knowledge, serial data is always available and diagnostic enable modes are triggered by specific resistances to ground . . . i.e. 10k mode etc. Have you confirmed all of the PCM power and ground circuits? All the way back to the battery? Is the PROM seated correctly? This is a known good PCM?

[RVChaser]

The car runs fine......just want the scanner to work if/when problems arise. I have fused and wired in all the power circuits....does the PCM case need to be grounded?

[86FieroSEv6]

No, it is not necessary to ground the case, often they are in plastic retaining brackets from the factory. Does the check engine light operate properly? i.e. Does it turn on with the key and go out after start? Further, you are probably not wired out from the PCM for a lockup converter so F was not installed to your ALDL . . . . ya'll aren't on stock automatics, are ya'? Does the broadcast code on the case sticker agree with the broadcast code on the prom sticker? Or, is there a Hypertech stuffed in it? Tell ya what, how about a picture of the open PROM bay on the PCM, that may help to decipher why you can't establish communication. Believe it or not, it may be that you are simply using the wrong year code when you entered the tenth character during vehicle ID. Or, maybe there was a different body code (third character) or engine code(eighth character). Is this the original PCM to the car? That service number comes up good for your car when I plugged it in at O'Reilly Auto Parts' online cataloging.

[RVChaser]

The gauges and dash are gone....no check engine light....no key. It's got a master kill switch, toggle and push start switch, ford solenoid and separate fan switch. Running an automatic (per rules). I assume (I've never worked on one of these PCM's before - was asked to rewire the car because of my electrical experience) the PROM is the memory, is it under what looks like a small cover on the PCM? It's the original PCM with no modifications and the spare parts car we have also has the same PCM. After I input the information on the scanner from the VIN the scanner shows the right year, make, model and engine. I'll take pictures today and send them.

Thanks for your patience with me!

RVChaser

[86FieroSEv6]

No problemo senor. New project, get an amber lamp from Radio Shack and wire in the check engine lamp circuit. It IS necessary. I'm no stranger to built up harnesses . . . .

http://www.youtube.com/watch?feature=player_profilepage&v=yALmUynDm2k

This thing is street legal and he drives it everywhere, sorta the same kind of punishment your car will go through.

[RVChaser]

Good idea with the light....the only problem I see is won't it constantly be on due to the fact we've removed so many components? Can I use just a 12v light? Also, our car will never see the road again....and just runs in circles!