Good morning all!
I ordered an ignition harness adapter from Summit Racing about three weeks ago and they say it isn't gonna be here until Jan 8! It is the adapter that is supposed to hook my Accel 300+ ignition and coil to the GM ignition module (small cap distributor) that I wired to my Ford distributor.
Here are the pinouts for the Accel ignition box. Would someone tell me where to hook them to the module? There are 4 pins on the ECM side and 2 pins on the coil side, right? What are the 4 ECM pins for and which are the coil + and - pins? Like I said, I already had some help figuring out which wires to hook up for the mag pickup...now I need to go the other way.
Many thanx in advance
1.) Main IGN power (hot in run, start or test)
2.) Ground to engine
3.) Tach lead
4.) Optional points trigger lead
5.) Coil +
6.) Coil -
7.) Mag pickup + (already wired to purple lead off of dizzy)
8.) Mag pickup - (already wired to orange lead off of dizzy)

 

See if these help.
This for an upgrade to the ford TFI coil.
I converted my IH motors to the Ford DS pickup to trigger the GM TBI. If you don't use the coil you won't need the ballast resistor.




Just Internationals FI

GM-ECM pin out for 8746

HTH

 

Thanks, Bill. Cool wiring diagram...two problems with it...
The Ford TFI coil is a full 12V coil. It doesn't need a ballast resistor. That one component is one that I have had a problem with since the first time I did the TFI-conversion on a Jeep engine. Whoever drew the original wiring diagram for the TFI conversion failed to take the resistor out of it during the cut-and-paste operation. I have thrown 600 VDC (pulsed) at an off-the-shelf TFI coil for about a year and it still works. That kind of voltage/current would have smoked a ballast resistor. I wonder how many guys have replaced DuraSpark boxes multiple times as a result of that one mistake. I now have an Accel racing coil (TFI) because I wanted the 48KV DC of spark it generates. This coil will handle every bit of the voltage/current/abuse that the black box can muster.
I still can't figure out where the wires connect to the ECM. The Accel diagram is ****-poor to say the least. It basically says to plug-and-play. Plug-and-play in this case sucks. They show a couple of wires that go to the coil and a bundle of wires going to the module. No color-coding is even attempted.
I guess the burning question is where the TACH lead goes to the ECM. The ECM needs a TACH signal, doesn't it? Another question is how the ECM can control timing with an ignition controller like this stuck between itself and the rest of the ignition system. What wire powers the in-cap module?
Jeez....does it ever end????
Thanks again, Bill...

 

I kinda thought you would want to get it running, then worry about adding the Accel later. There is a lot of tuning/learning that can be done without the accel installed.
I understand if you must have the accel in there before you fire it.
I'll check the ford diagrams for the TFI harness. Thanks for the tip.
EDIT: check several sites, some still have the ballast or resistor wire listed so it off to the ford wiring diagrams.
I don't have to run 6,000 rpm to get the torque I need to wheel so an after market ignition was never really in my plans.
We wheel farm equipment!!! Just converting to the TBI was good enough for me.


So how close are you to having it on the road?

Here is the adapter you ordered(I think). You won't have to do anything but plug and play the way it looks.

 

Yep...that'd be the exact harness adapter I am talking about. It cost me $70 from Summit racing. I was trying to find a way to fab up my own harness so I could send that expensive SOB back to Summit before I even took it outta the blasted box. That $70 would go a long way toward other Jeep project stuff...like a new front driveshaft to replace the one my carb'd 360 twisted out.
I have to have the Accel in there before it fires because I clipped all of the wires for the DuraCrap when I put the Accel box and ProJection in the Jeep about a year ago. I figure it is best to tune the engine like I plan to drive it and learn from there.
The TFI coil may show in the diagrams as needing a resistor, but trust me on this...it doesn't need it. I have been running the SAME coil that I ran off a DuraCrap box for about a year off the Accel 300+ box and it hasn't skipped a beat yet. The specs show it as being able to hold a sustained 12VDC input on the primary windings. I threw a LOT of volts at it for a long time and it still works really well...it's my carry-along spare in case the Accel coil (part # 140009) craps out on me at the worst possible opportunity. Keep your plugs gapped out to about 0.040" and you will like the results. Your engine might like a little more or less. The mfr's spec of 0.035" is off by a lot IMO. I run 0.044" gaps.
As for getting it on the road...I am waiting on a few things:
1.) That pesky Accel adapter harness
2.) AutoPROM or PROMinator
3.) VSS buffer
4.) Me to get industrious enough to go actually wire the fuel pump up to the Jeep.
One last question...if you look at that Accel harness adapter, the OEM coil connector shows a 2-wire connector that goes to the coil. The one I have that came off the donor vehicle only has one 12-ga red wire. I am assuming that the connector in question simply feeds a 12VDC current flow to the coil in RUN/START/TEST. Could that possibly be the main power feed to the Accel box? If so, I am in definite business and I don't have to cobble together another harness to adapt that part to my CJ's electrical system.
Thanks Bill...keep the rpms below 6000...my peak torque comes in at about 4000 rpm (390 lb ft) and my peak HP is about 373 HP @ 5000 rpm. That's plenty to kill a few Rustangs on the roads of Corpus Christi...and run over 'em afterwards.
Keep on wheelin'!!!

 

Here's a "revised" diagram of my question. The circled part is the part in question. To me, it looks like this may be the primary feed to the Accel box. The module (in-cap) fires the coil through the box using this 12 VDC feed as primary voltage. I see the plug and play part now. The ECM wiring is left intact and the Accel box simply wires between the dizzy/module and the coil, replacing the 12VDC feed to the coil from the vehicle's IGN wiring with a 600VDC pulse to the coil...Gawd how I love modern electronics!!! A 48000VDC spark pulse is just wonderful for a 24 year old engine...
Am I on the right track here? I am thinking I can just take a replacement GM coil connector from the local parts house and wire it to a 12V IGN feed to power the whole contraption.

 

Oops...forgot to attach the pic to the last post. Here it is...sorry.

 

IIRC it's just the 12V on the pink wire and the small white wire is for a tach.
I run the pink to a separate power relay and just energize it with the ignition so I don't get a voltage loss from the old IH wiring. I also tie the injector 12v to the same relay.

Have you checked out jagsthatrun for the VSS?

 

Well, I just got off the phone with Summit Racing and I am a bit pissed off. When I ordered that damn Accel harness, they told me it would ship by today. Upon checking with them on the WWW site I decided to call since their status messages are somewhat ambiguous. Sure enough, the "Expected Arrival Date" of 01/08/04 is the date the harness is expected to arrive at Summit from Accel.
So, gents...screw that harness. Let's see if we can come up with the same thing. Look at the post above and you will see the diagram of the Accel harness that is costing me $70. Here's what I have to go with...
The large connector has 4 wires going to it. They are (from top to bottom):
1.) RED: IGN hot in RUN or START
2.) BLK: GND (easy enough)
3.) BRN: Coil NEG
4.) YLW: Coil POS

The other connector actually has 4 wires as well, but it would appear that only two of them are used in this case. The two you can see in this diagram are (top to bottom again):
1.) PPL: Mag pickup POS
2.) ORN: Mag pickup NEG

Just below the PPL wire is a GRN wire that is used as a TACH SIGNAL lead...probably not used in this application. Below the ORN wire is a WHT wire that is a points trigger lead...definitely not used in this application.
Questions:
1.) On the GM module, there is a separate connector for the coil. The C+ is probably coil POS, right? Well, are these simply a flow-through signal from the mag pickup to fire the coil or does this actually send primary voltage to the coil?
2.) The pink wire just goes to an IGN HOT (RUN or START), right? If so, there's the source of power for the RED wire described above. Easy.
3.) The PPL and ORN wires from the ACCEL 300+ box are the mag pickup leads. Would wiring them to the coil terminals on the GM Module be a bad thing?
TIA...let's see if we can get this Jeep running today, fellas!

 

Okay...
I am looking at a very detailed diagram of the 1228746 wiring. (Thanks, Bill-usn1.) It shows an internal view of the EST distributor and the module. The diagram shows C and + as being two different terminals. They come off of some kind of switch/gates. the C terminal is wired to the coil via the BLK wire on the connector and the + terminal is wired to the coil via the PNK-BLK wire. The + terminal is also shunted to ground through a capacitor that is internal to the module.
So, from this diagram, I am starting to think that it would be safe to wire the mag pickup leads to these two terminals. I think I should wire them up with the mag pickup + going to the C terminal and the mag pickup - to the module + terminal. Why this config? Because what is labeled on the module as the + terminal is actually shunted to ground. If I get 'em backwards, the timing will be horribly screwed up and I can just reverse them as needed.
It also looks like I can use that pink wire as a source of RUN/START HOT power for the box. Actually, I don't even need the pink wire because I can just wire the whole thing to the Jeep IGN hot lead.
Whaddya think, guys?

 

I got a response from Accel today...about 2 hours after I emailed my question to them. They responded with the standard "Orange wire to -, Purple wire to +" answer. That helps some of it, but I am still wondering if I am about to blow something up by wiring the mag pickup leads to the +C terminals on the module. I looked at the diagrams again and decided to reverse my earlier decision. I figured out which went to what side of the coil. The C terminal is wired to the coil neg side and the + terminal is wored to the coil neg side.
Will someone please reassure me that I am not about to burn up a module, an ECM, and a $200 ignition unit? Help!!!

 

Because I run the DS on an IH, it turns oposite of the GM dist. Therefore I hook the purple to P and the org to N.
You are right in that if it is backwards the timing will really be screwed up.

Will it burn it up...No BTDT.
Set the timing at 0 or 10 or what ever your base is (10*) and you will know if it's right as soon as you fire it up. If it fires up.
The only thing you should have on the coil is the 12v from the ign.
I power all my system through a relay to prevent a power drop in the stock vehicle wiring.
Just use the ign wire that used to go to the + coil to energize the relay for your coil and your + side of the injectors(red and white)

 

Yeah, I have accidentally reversed them before and the results were a horribly screwed up engine until I figured it out.
So, the + and C terminals on the module don't feed any voltage to the coil? Are they a trigger mechanism to fire the coil? What did you wire them to?
I have the wires wired just like you do...purple to P and orange to N. My dist turns CW. The GM dist turns CCW.
I run about 6* of base timing because I have the CDI and a plug gap of about 0.044".
Thanks again, Bill.
EDIT: BTW, I cancelled that order for the ludicrous $70 adapter harness from Accel. I had ordered it from Summit. I credited the $$ to a better purchase...a new Hurst ProMatic II shifter to replace the old beat-up B&M shifter I have. I'll fix the B&M shifter up and use later down the road.

 

Your base timing is determined by the chip you are running. If the base is 9.8 then that's what you should be set at.
Unless you are trying to compensate for it pinging and need to retard it 3*. Don't try to go by what you had before the computer, it's all in the chip now.

The B1 and B2 terminals are tied together. They are your sw 12v ignition. It passes right through to the EST.
The blk? (I thought mine was white) goes to C as shown.

Basic GM color code is Pink/blk is sw 12v
Org is fused 12v(unless it's the serial data)
red is bat 12v
blk/wht is gnd

 

Oops...setback time. So the B1 and B2 terminals are a switched 12V feed to the coil. That PINK wire is simply a 12V feed during cranking? Hmmm. How are they switched? Directly off the IGN switch, or are they switched internally in the dizzy module by the pickup coil? I know it seems like I'm nit picking here, but that switching may be the coil trigger mechanism if I am looking at this in the right way.
So, when someone wires up an MSD box to one of these modules, where does the trigger signal come from? With a standard small-cap dizzy, there is no need to wire the pickup (like we have done) to the module. The only connections that are made go to the + and C terminals on the module's exterior, right? Something has to tell the module to trigger the coil. Wiring up an aftermarket ignition like MSD or Accel seems like it simply places the new ignition box in the circuit between the module (at +C) and the coil. It takes the old coil wiring completely out of the picture and replaces it with the new box and wiring.

 

If you look at the short wire between the 2 long ones it's says Ign sw. that is your coil B+.

IIRC, if you want to run your system fuel only like Howell, they use the pl/wht lead going to B5 and run it to the neg side of the coil with a filter in line to protect the ECM.
I would not try to understand the EST just from that simplified block diagram!

 

CLICK! That answered it. The B+ from the PINK wire supplies current to the coil AND to the EST THROUGH the coil in parallel. The + and C pins on the module don't supply any current TO the coil...they receive current FROM the coil via B1. The EST triggers the coil to fire internally through the amp.
Okay, now this is going somewhere good. (Sounds like an ex-girlfriend of mine... ) I wonder what the voltage on the purple and orange wires is supposed to be (from the OEM DuraSpark boxes)...maybe a 12V signal? I can't believe I didn't think to look at it like this.
Bill, you da MAN!!!:hail:
EDIT: Bill, I am about to draw up a little diagram in MS Paint and email it to you. I guess the burning question here is "What exactly will happen if I do in fact wire the PUR and ORN wires from the Accel 300+ box to the + and C terminals on the module?"

 

I'll have to review it in the morning. I only have 5 hrs left till I get back up for work!
:lala:

 

Okay. I'll TRY to post the file here too for others to look at.
The "See note in email" simply refers to the fact that those wires (also orange and purple to correspond with the mag pickup wires) are supposed to wire to the OEM mag pickup in the dizzy before I wired the GM module to it. Once these two wires (or these two terminals) are filled, the Jeep just might fire off tomorrow sometime...after I actually solder the harness together. The brown and yellow wires are the coil + and - wires and could be carrying as much as 600VDC pulsed to the coil...definitely don't put THESE wires onto the module + and C terminals.