1972 Coupe Deville Dashboard Warning Light Issue and now also starting issue

[Caddi]

Hello! I bought my 72 CDV few months ago. One of the issues I’ve been dealing with are malfunctioning warning lights on the instrument panel. The only lights lighting up are Stop eng Temp light (while driver door is open) and generator light. Also the right turn signal indicator light is out. There were couple of missing lamp sockets, which I installed, along with new bulbs. All of the other lights on the dashboard are working, including gas gauge.

So, I started checking the circuit diagram and noticed that seat belt warning buzzer connects to the warning lights and exactly to the ones that are out. I started looking for the seat belt buzzer. First,  there was no sign of seat belt warning switch next to the neutral safety and back up lamp switch on the steering column. Well, maybe somebody got rid of the switch and buzzer. Then, I went to check for wires, expecting to see some poorly made connections. The pink wire from fuse block to seat warning buzzer and to instrument panel connector #5 was solid. There should be a black wire going to connector #18. Well, this connector was empty. As I was reading the forum, there were couple of mentions that early 72’s might not have the seat belt warning buzzer. My serial # is 6444. Any other 72 CDV owners here with no seat belt warning buzzer?

Now that my theory of poorly made buzzer deletion doesn’t seem to be the case, I’m out of ideas.

Another electrical issue I’m having is, that right side back up light and right side cornering lights are out. I confirmed that both locations are getting juice. I cleaned both sockets.  I’ve also cleaned ground connections at the steering wheel bracket and the front light ground as well.

OK, the above was written few days ago. Tonight, as I was going to move the car, it didn’t start. This time Brake, Gen and Water warning lights lid up as I was trying to start but nothing else happened. I drained the battery while going through electrical stuff during the past few days, so I used a jumper. When I turned the ignition to start, the interior lights didn’t dim, so I’m assuming there should be enough juice coming from my jumper. I heard no clicks from the starter solenoid.  I guess my next step is to jump the neutral safety switch.

It was just curious to see all of those other warning lights lid up though with the starting issue. Definitely not making the troubleshooting any easier, in my opinion.

Or, maybe it’s my ignition lock cylinder or starter switch. When I tried to start, there were two times that my ignition lock got stuck in the start position. The ignition lock has been kind of stiff since I bought the car…

I should also mention, that it’s been hard to crank the engine when it’s hot. This car has headers though, so I’ve been thinking it’s the heat that caused this. Maybe not…

[Scot Minesinger]

The hard to crank when engine is hot thing is usually the starter beginning to weaken and it probably needs to be replaced.  There was a factory heat shield to protect the starter from exhaust, which was a small piece of sheet metal.  I made a new heat shield that was better suited to the my 1970 DVC with dual exhausts to protect the starter and wiring.  It has worked well for nearly a decade now.  Although I did loose a starter in 2013 - it was the solenoid, not the windings.

All the other stuff, you are going to take a very intense looks at any modifications (you have headers already).  When there are malfunctions in these Cadillacs, I look to the modification work and it usually turns up. 

Next place is compromised wire insulation - this often happens at the door hinge, when the the rubber conduit protecting the wires from sheet metal edges on door and body (kind of a dual grommets connected by flex rubber hose) - the rubber fails and the wires get cuts and intermittent electrical issues result.  You mentioned something different happened with door open, so take a look there.  Happens a lot on 1965-1968 Cadillac door rubber conduits, but not much on the 1969 and newer.  Since you write about buzzer and all which interfaces with door - this may be a good place to start.

Good luck, these electrical issues are so fun and such a rich experience.

[Caddi]

The starting issue was neutral safety switch. The plastic switch part was loose and pushing it back made the car start again, albeit cranking was slow, even when the engine was cold. Could a bad connection at the neutral safety switch cause a sluggish cranking?

[Scot Minesinger]

A loose NS usually does not cause sluggish cranking because it is a relay circuit.  Sluggish cranking can be poor electrical connections in addition to of course a weak starter.  Check ground strap to frame at starter, that often is an issue.  Of course check battery cable connections - all four (five including body ground).  Check battery voltage and then you can use an amp probe.  Also you could take it to a parts store to test battery - I worry because they seem to diagnose issues in their best short term interest.