70 Mach 1 MSD ignition Troubleshooting, Pics, Etc, Etc

stackz · Oct 8, 2004

ok, a 70 mach 1 came into the shop today, actually a pretty nice car overall. Problem is...after the guy got the engine, etc installed the car dies on him unless he unhooks the battery.

Took one look at the bay and it looks at first glance like the msd system is installed wrong and might be on continually draining the battery. I havent dealt with msd stuff in a while since we've been on a duraspark kick for the past two years here. Anyway, he doesn't want to convert to duraspark....

soo....he also couldn't provide the wiring diagrams for the distributor/ignition/etc.

I will provide some pics of the system below. I would love it if anyone could provide wiring diagrams of a 69-70 engine harness and underhood harness as well as if anyone can identify the distributor?? looks like a magneto. If anyone knows where the diagram for the 6AL is also, that would be wonderful. Also, if anyone can identify the two relays in the system...that would help lol. I've never seen those two goofy things before even when I was messing with msd stuff.

P.S. if you want bigger pics, simply take the "-med" out of the pic link descriptor:

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WORTH · Oct 8, 2004

send me an email at acrad@adelphia.net and I'll send you the factory diagram.

gp001 · Oct 8, 2004

Since it has an MSD distrib the connections should be:

Large Red - to battery (+)
Large Black - to ground

Small Red - to ignition 12v source
small black - to (-) of coil
small orange - to (+) of coil
violet & Green wires - plug into lead on distributor
white wire - not used

gp001 · Oct 8, 2004

Also, I'm guessin the relays are for the fan(s). The relay attched to the bracket looks to be a thermo relay (probe coming out of it). It looks to be fed power by the pink wire (from the top) and triggered by the blue wire. It then feeds the black relay on the other side of the support, which looks like it powers the pusher fan. My guess is there is a problem in that circuit

stackz · Oct 9, 2004

hmmm that fan idea could be the problem then, but I wonder why it's wired into the msd then if they're fan relays?

I traced the wires and they connect into the msd 6AL box. I'll do a little more digging later today, thanks for the wiring info guys. Lets see what I can find.

gp001 · Oct 9, 2004

Which wire(s) are connected to the MSD? And, what wire(s) are they connected to on the MSD?

The MSD should be wired separately. It doesn't like to share power. Make sure it is wired as described above.

It could be that they split the trigger wire to trigger both the MSD and the thermostat control using the same source.

I would disconnect the trigger wire to the thermostat relay and see if it has an affect (ie battery not dying overnight).

ratio411 · Oct 9, 2004

It looks like they want the fan control thermostat to power up when the engine is on, so they triggered it from the ignition wiring.
That is the right idea, but wrong connection to make. They should have used a separate circuit that is powered up by the 'ignition' side of the key switch, not the ignition itself.

I don't see a voltage regulator...
Does this thing have a 'one wire' alternator?
They are notorious for draining the battery overnight. It is a problem with the internal regulator and an alternator shop would have it corrected in 3.46743 minutes.
Dave

ratio411 · Oct 9, 2004

I will attempt to remember the test for the one wire problem...
My uncle told me how a while back to check mine.
Unhook the postive cable from the battery.
Unhook the wire from the alternator.
Make sure the key is OFF.
Use a 12v test light...
Hook the ground clamp to the battery positive.
Touch the test light side to the wire post on the one wire alternator.
If the bulb lights, and the key is off, your alternator is draining the battery.
Dave

stackz · Oct 9, 2004

I'll look more into it tomorrow, we've been in the middle of an intensive 3 explorer 3 engine swap marathon yesterday and today haha. 3 engines with blown head gaskets and the only way to swap gaskets is to pull the engines eesh.

anyway, I tossed a battery in it and apparently the problem is farther along. I'm thinking that the ignition switch is bad. here's why.

You turn the key on along with the toggle switch and crank the engine with the key. After the engine is running you let off the key so it goes to the run position but the starter is still turning so you simply turn the key all the way off to kill the starter and in order to kill the engine you turn off the toggle switch, LOL.

So I'm thinking either the ignition on the column is bad or they got some wire crossed somewhere which is why they wired the fan and msd together and in turn both to the toggle switch.

this is what I'm thinking, anyone think this is a sound assumption.

oh and WORTH thank you for the pdf file but for some reason I cant save my attachments, I'll keep trying though.

70 Mach 1 MSD ignition Troubleshooting, Pics, Etc, Etc

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