I broke my starting system

[CoronetDarter]

Yep, I did it this time. Usually when I break something on car, after a bit of troubleshooting I figure it out, a lot of times by pure luck. In this case, my 69 Coronet has a no crank issue and after the better part of 4 weekends including six hours today I'm still at square one.
First the back story. I had the IP out as the speedo needed rebuilding. The speedo cable was resting on one of the header tubes, melting the outside jacket and essentially welded it to the cable. The sudden resistance burnt/broke the speedo mechanism. Got the repaired speedo back from JC Auto Restorations (which I highly recommend BTW) and I got ready to reinstall. While waiting on the repair I replaced some of the LED lights in the PCB. With just the PCB resting on the steering column, the circular wiring harness plugged in and a jumper running from the RTE voltage limiter to ground not only was I able to test the LED lights but actually started the car. Two weeks later I install the speedo into the IP, secure the PCB to the rear of the IP, plugged in the circular harness, and reinstalled the IP into the dash frame. At this point I tested the LED lights again in Acc mode, go to start the car just for S&G before I get too far, and nothing. No crank. Accessory and Run both work as the lights go on and the electric fuel pump starts up. Turn to Start and its like someone removed the battery. In Run, there's nothing when I jump the Batt --> Sol terminals on the starter relay. There's 12.94 V at the yellow wire at Start, 0V at SOL. Seems pretty straightforward, I get a new starter relay from Ehrenberg on E-bay, same result. Next (which I should have done originally), I swapped the new starter relay over to the Dart and it fired right up. So now the new starter relay is in back in the Coronet.

 

[CoronetDarter]

It's an auto, so using a jumper I grounded the NSS terminal on the starter relay to the engine; no change.

The battery is in the trunk along with a Ford-type solenoid to cut the power to the 1/0 cable during non-crank. The batt side of the solenoid has 12.94 V. The 1/0 cable goes from the switched side of the solenoid directly to the starter. The exciter wire on the small switched terminal of the solenoid goes to the SOL terminal on the starter solenoid. The continuity of the wire is good.

To bypass the Ford solenoid, I disconnected the switched exciter wire and jumpered it directly to Batt+ on the battery. The starter relay began chattering and there was only 3.94V at the SOL terminal (should've been 12.9V I believe). Hmm, sounds like a grounding issue.

 

[CoronetDarter]

Grounds do matter. There is a ground wire from the dash frame stud to the steering column jacket. That wire is secure at both ends. For S&Gs I disconnected the wire; the voltage at the starter relay Batt stud dropped to 3.94V. So grounds make a difference.
But now I'm stumped as to what circuit or connection I disturbed while reinstalling the IP.
Before calling it a day today I pulled the IP and tomorrow I'll try to replicate the PCB testing that I had done earlier.
Does anyone have a suggestion on what I should test while the IP is out?

 

[Geoff 2]

Is the engine grounded to the body? It should be.

 

[CoronetDarter]

Is the engine grounded to the body? It should be.

Yes, there are two ground straps. One is the factory strap from the intake manifold to the firewall, and there's another 1/0 wire from the engine to the frame.

 

[NoCar2023]

I would verify the trigger circuits on both the relay and solenoid will carry the load of an incandescent test lamp when cranking.

 

[NoCar2023]

Or maybe a battery ground issue?

 

[Kern Dog]

With electrical problems, I'm still stuck at the "replace parts until it starts" stage.

 

[NoCar2023]

Simple load test using a headlamp.

 

[Don Frelier]

First double check battery connection which you likely already did.
I would suggest taking a jump cable or heavy gauge cable and connect as solidly as possible across each section of primary wire. One section at a time.
You probably have a bad cable.

 

[CoronetDarter]

Or maybe a battery ground issue?
View attachment 1471323

Yep, this is how I set up my car.
And you're closest to the answer. This morning I did two things: I added a star washer and a large circumference washer to the underside of the steering column ground wire I mentioned in the prior thread, then tightened up the steering column.

Next, I swapped over the battery from the Dart. The Coronet fired right up! Put the Coronet battery in the Dart and it fired right up. Swapped the Coronet battery back into the trunk, and the the engine fired right up! Talk about ghosts in the machine. The water level in the battery was good, the cables were secured tightly. I didn't do anything to the battery or the cable.
Hard to believe that an improper ground at the steering column has that much effect on the starting circuit.
No matter, now I put my dash back together.

 

[CoronetDarter]

First double check battery connection which you likely already did.
I would suggest taking a jump cable or heavy gauge cable and connect as solidly as possible across each section of primary wire. One section at a time.
You probably have a bad cable.

The irony is that I checked the connections when I was bypassing the Ford solenoid. Connections were tight, no corrosion at the batt terminals. The battery is a 3 year old Interstate that I bought at Costco.
The battery is in a battery box with 1/0 cables. The negative cable is secured to the body by the trunk hinge, paint scraped away. Being the battery is fairly new and the engine fired right up a few weeks ago, I assumed it was me buggering something while installing the IP.
At this point I don't know if the fix was the battery connections or the ground wire. I have to drop the steering column again to install the switch panel; I'll isolate the ground wire at the time and see what happens.

 

[CoronetDarter]

With electrical problems, I'm still stuck at the "replace parts until it starts" stage.

I stopped at the starter relay.
It helps to just walk away to get a fresh perspective. Yesterday was spent bypassing relays and solenoids to try to isolate the supposedly defective part. I couldn't wrap my mind around why the SOL terminal was 0V when the yellow wire was 12.9V at crank. I honestly still don't know why, other than I "fixed" it.
It was only today that I decided to concentrate on the battery and the steering column ground wire.

 

[Kern Dog]

I have encountered many electrical issues that made no sense to me. I've often changed a coil, a distributor, ballast resistor or ECU and suddenly, the car will start so I blame the last part that I changed.
Let's say I changed the coil and the car will now start. I'll sometimes take that coil and try it on another car to see if is is actually bad. Sometimes it isn't so I'll save it. Loose or poor connections seems to be the cause many times.

 

[CoronetDarter]

I have encountered many electrical issues that made no sense to me. I've often changed a coil, a distributor, ballast resistor or ECU and suddenly, the car will start so I blame the last part that I changed.
Let's say I changed the coil and the car will now start. I'll sometimes take that coil and try it on another car to see if is is actually bad. Sometimes it isn't so I'll save it. Loose or poor connections seems to be the cause many times.

Same here. I'm adding the starter relay to my parts stash of known-good parts.
Buttoned up the dash, steering column, etc. and took the Coronet on a short cruise around downtown Lincoln. Everything works - for now.

 

[CoronetDarter]

In retrospect, I'm pissed that I didn't follow the #1 Rule of What Did You Touch Last? The car started when I was testing the PCB and then didn't start when I installed the IP. Instead of dicking around bypassing relays and solenoids and performing continuity checks in places I hadn't touched (trunk, engine compartment) I should've concentrated on the dash from the start.