View Full Version : Some help with electronics

08-16-2007, 03:33 PM
Hey Guys and Gals

I am new member to this site I have had a 1973 convertible Centurion for three years now (I have not registered it to the site yet but will) I had not had a problem with it till this past week and in trying to locate parts I happened across the site WHAT A GREAT PLACE!!! Thank you for putting together something like this. Well let me get to the question that has brought me here.

The car refused to start this past Friday so I did not have the time to look into myself so I handed it over to my trusty mechanic. In his diagnosis of the problem he found a computer board that he believes to be fried (visual inspection leads me to believe it as well) since I can not seem to locate a wiring diagram for a 1973 Centurion we are speculating that is an ignition control electrical board. The case (red plastic) and the electrical board that is contained in the red case are actually located in the glove box of my car. The red case is stamped with "SOLID STATE AC CONTROL". The board inside this case is the one believed to be bad. So I suppose I am looking for two things if any one out there can help me...

1) Are we correct that the board is an ignition control board (amongst possibly controlling other things)

2) Where on GOD'S green earth might I look to find another? I have had a bit of a struggle trying to find engine parts but trying to locate something like this is entirely different.

I thank you in advance for any advice or suggestions on this matter and I truly look forward to being a member of the Centurion web community.

08-16-2007, 04:09 PM
Wow, sounds like some aftermarket part to me. Got a picture?

Welcome to the board!

centurion 455 ragtop
08-16-2007, 04:48 PM

First off, welcome to the board. You will find only good people always looking to help out.

Second: Find yourself another mechanic. :spank: If he thinks this is a factory unit :Dou: and cannot figure out the wiring...oui vey:Dou: find another one and hold on to your wallet.

The factory stock ignition for all 1973 Buicks is a points & condensor style distributor with a coil. I am pretty sure in 1974 they switch to the electronic ignition distributor (HEI) Its a big looking distributor, bulky but very reliable. I installed one two years ago.

There was never a factory installed or dealer installed computer or computer board in the 1973 model year for any Buick and or Centurion. Computers were not even invented yet except for those the size of a small houses owned by the govt. Furthermore there is no red sealed ignition box for this car factory installed.

Just recently I had my entire dashboard removed and apart on my 73 Centurion convert, repairing some wiring and installing some options. I'm telling you Jason it's aftermarket that's in your car. It sounds like it may be something of an aftermarket ignition such as an MSD 6A unit, which comes to my mind and is in red in color and is a sealed unit. Or some other brand such as Mallory, Stinger Ignition or Petronix ignition. A previous owner most likely installed it and it worked fine until it puked on you. If this is the case, rip it all out and install a factory Delco-Remy rebuilt HEI distributor. Should be around $100 bucks. You will also need to replace the ignition wires with HEI wires. Or you can go on line Summit or Jegs) and order an aftermarket HEI distributor and wires, but those will cost more. It takes about an hour to install.

If you can Jason post a photo of it. We will be able to help you along further. If you are looking for parts or advise, etc., just ask Pal. There are plenty of us on line here that can help.

Good luck, and please keep us posted.

08-17-2007, 09:19 AM
Hey Guys

Thanks so much for the quick replies about my problem. I spoke with my mechanic again last nite and he swears to me that the circuit board is original, Ragtop I forward your response to him (edited a bit) and this is what he came back with.

"I do not think it is a ignition module. The ignition feed for the coil runs through the box. It is definately a factory part. It is located next to the glove box not in it. It is a module of some sort not a computer. Go ahead and post the pictures and one of those guys will no what it is. Ps the wiring does go to a speed sensor on left front wheel and a sensor on the trans. My guess is the only thing the ignition has to do with this box is that it powers it up."

So in the efforts to figure out what this device is I was able to take some pictures of it and they are attached.

Thanks so much to all for lending a hand on this.

08-17-2007, 09:57 AM
Mac Trac

Brad Conley
08-17-2007, 10:52 AM
Mac Trac

Actually, MaxTrac, with an "X"...:laugh:

This is a early traction control device...I would guess <1% of 73 models were equipped with the option. Getting replacement parts should prove interesting, if not impossible.

Added in edit: see http://en.wikipedia.org/wiki/Traction_control for an explanation of MaxTrac.

08-17-2007, 03:33 PM

centurion 455 ragtop
08-17-2007, 04:17 PM
OK, I got some egg on my face :Dou: (prefer scrambled:laugh: ) Sorry I jumped the gun here, just tired of hearing people getting taken for a ride. Anyway did some digging. The following posts will show the Max Trac and trouble shooting. Its taken from the 1973 Buick Chassis Service Manual. THis should help you.

centurion 455 ragtop
08-17-2007, 04:17 PM
Page 2

centurion 455 ragtop
08-17-2007, 04:18 PM
page 3

centurion 455 ragtop
08-17-2007, 04:19 PM
page 4 Your problem may be on this page. I would try and re-hook the box back up and try shutting off the switch. If your car runs, then just leave it alone, unless or until you can find another box.

centurion 455 ragtop
08-17-2007, 04:19 PM
page 5

centurion 455 ragtop
08-17-2007, 04:20 PM
page 6