68XR7 electrical issues

This summer driving my XR7 started running rough and died. Was able to restart a couple of times thinking I could limp it home then nothing, no power to anything whatsoever and had to tow it home. Replaced neutral safety switch with repro from WCCC, had to jump at solenoid to start but got it running. Ran for a couple days starting now with ignition switch. Took it for a short ride and all of a sudden no power whatsoever and another tow home. Began checking for obvious issues and found starter cable from solenoid to starter worn with wire exposed, replaced and jumped again from solenoid after which it was starting again with ignition switch. Started numerous times and drove longer distances but eventually just died while driving and another tow home. Electrical is not my strong suit or even my thing so did have someone more familiar test with multimeter. Battery is good and holding charge, power at coil, but only 2 volts at ignition switch and nothing at fuse box. Fusible links do not appear fried though all wiring under hood is very brittle. PO installed extra connections at solenoid not sure where they lead, one may to be to additional fan that was installed; there are 4 total on that side besides the battery. Am thinking I should buy new under hood harness due to the poor condition of the wiring but not sure that will solve the issue, and while necessary is an expensive purchase if it doesn’t remedy the issue. Any input/thoughts on what may be causing this or if a new harness will solve it?

Sounds like you have a bad tachometer which is not uncommon. Bypass it to confirm. Easy to do - just remove the ash tray, then the ash tray surround to access the wires. Takes 5 minutes / three screws.

Could be a number of things: bad ground, corrosion at battery terminal connectors, alternator not working. When the car is running, check the battery voltage: it should be 14.0 to 14.8 or so, not 12.X. The latter would indicate a no charging situation.

I don’t believe the 68 had any fusible links.

Any chance you have those battery terminals that have two bolts that clamp down the cable?

And then therr is the problem i had, it was a bad connection at the back of tge ignition switch. Hit a bump, any bump, expansion joint whatever it died.

Replaced. The switch. Ok for over a year now. Something to keep in mind

Thanks, I will keep in mind. I have the switch out right now as trying to trace back why there are only 2 volts at switch.

Yes the terminals are the bolt down type. I recently replaced the positive cable as it looked a little iffy. Cleaned the terminal and clamp on the other side.

Can you help me understand how the tach would be related to the problem?

As I responded to xr7g428 I have replaced the positive battery cable and cleaned the other side. I would check the battery voltage with the car running but am not able to start it even from the solenoid at this point. If the alternator wasn’t working wouldn’t that cause the battery to drain and lose its charge? That hasn’t been the case as it is holding a charge but no power to anything, no headlights, no taillights, just plain nothing. I am supposed to be putting it away for the winter in storage next week (Wisconsin winters are tough) but can’t get it running to drive it to storage.

The tach on all Ford products of the era are in series with the coil. If the tach is unplugged or failed the car doesn’t run.

If you don’t have power to anything it should be really simple to find out where the problem is. A meter is what you need, set to read12 volts DC.

Check your ground cable to the engine block and the cable from the back of the passenger-side head to the firewall.

You need to look for voltage across connections. That means putting one probe on the battery post and the other on the exposed part of the cable. You can only measure voltage across a resistance. There should be no resistance in those connections.

I think you will find that replacing the other cable will fix this but measure and test before throwing parts and money at it.

For voltage almost any cheap multi meter will do. Harbor Freight has them for less than $10.

Thanks for the suggestions guys. I did disconnect the tach but still won’t start so don’t believe that is the issue. Grounds appear solid and connected. I am getting frustrated and running out of time and may need to tow it in to a shop. Anyone have any recommendations in the Milwaukee, Wisconsin area?

Use a volt meter to find exactly where the issue is. Put the + terminal of the meter on the + terminal of the battery. Then measure the ground to see where exactly the problem is.

Hello, I might have a suggestion. Check your connector going to your voltage regulator, it might be that if you hit a bump it creates bad contact, shutting down your engine. Do you also have those caps that go over the solenoid threaded posts instead of the eyelets? I have heard of those being very bad, making bad contact and even blowing off. If all else fails, if you can start the engine, just start wiggling connections and see what kills it.

Royce suggestion is spot on. (as per normal)… If have NO power, should be a simple one to trace down.

I’d start using a volt meter to test the negitive connection between battery & block, Sure sounds like a bad ground so check you have a good connection between the negitive post on the battery and any place else with exposed metal.

If that is good, then check connection between battery and starter solenoid. Then trace from there.

Hopefully an easy fix.