Author Topic: 1968 Coupe DeVille electrical issues  (Read 355 times)

Offline BigggBender

  • Posts: 8
  • Name: Daniel Bender
1968 Coupe DeVille electrical issues
« on: September 05, 2017, 09:44:40 AM »
Hi guys,

I am new to this forum and the world of classic Cadillacs and of course I already have some problems.

I recently bought  a beautiful 1968 DeVille in pretty good original condition and drove her for a few weeks here in the greater Detroit area. Super happy with the car but last Saturday the power windows gave out. I thought it might just be a blown fuse, but later I realized that also break light, door buzzer, horn and interior lights aren't working either. Looks like they are all on the same circuit on the fuse box, so I guess there is something like a main power cable that has an issue somewhere.

I have a wiring diagram of sorts, but it's a really bad copy and it's hard to make out any details. Maybe someone here has a better digital version of one, or can tell me where to find one until I can acquire a shop manual.

Also if someone has an idea where the problem could be (any relays between the battery and the fuse box maybe?) I am grateful for every tip and hint I can get.

Like I said, I'm new to the world of Cadillacs, not a total beginner concerning working on cars, but also far from being a professional...

Thanks in advance!

Daniel


Offline Highwayman68

  • Posts: 133
  • 68 Fleetwood Brougham
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  • Name: Mark Demyan
Re: 1968 Coupe DeVille electrical issues
« Reply #1 on: September 05, 2017, 10:17:14 AM »
Hi Daniel and welcome.

FIRST: You must order a Shop Manual and Body manual. They are available on ebay and possibly other sites too at reasonable prices. They will help with many little issues that you will run into. I find the digital version helpful when trying to search the manual. Plus you can enlarge the viewing in Adobe.

Lower the fuse block, located under the dash on the left side.

Look for a B/R wire on the back feeding the lower four positions and verify that there is 12VDC on the terminal. I am suspecting that you will not. This is the feed directly off of the starter. It is possible that the fused link located near the starter is blown or that the wire is no longer connected to the starter. This feed splits in the engine compartment and also feeds the blower, you should check to see if the blower is working to help know where the issue might be.

Let us know how this checks out and if more help is needed.

Mark

Offline BigggBender

  • Posts: 8
  • Name: Daniel Bender
Re: 1968 Coupe DeVille electrical issues
« Reply #2 on: September 05, 2017, 10:56:42 AM »
Hey Mark,

thanks, that is precisely the info I was hoping for, that gives me a starting point. You are right, there is no 12V on that cable.

I will definitely order the shop manual, but that's going to take a few days to get here, so I wanted to get a head start. I also might have to replace the engine loom in any case, there's a bunch of brittle wires everywhere.

Thanks again, I'll post again once I located the problem or in case I find more...:)

Online 35-709

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Re: 1968 Coupe DeVille electrical issues
« Reply #3 on: September 05, 2017, 07:33:46 PM »
If it is one of the fusible link wires, be sure to replace that fusible link wire with with the same number wire and the same length.  Length and wire size are both important with fusible links.  DO NOT replace those wires with just a plain piece of wire, fusible link wire is required there.  Fusible link wire is readily available at NAPA or any good auto parts store. 
Not sure about the '68s but I do believe you will find more than one fusible link wire coming off the starter --- replace them all while you are at it.
1935 Cadillac Sedan resto-mod "Big Red"
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Offline DeVille68

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Re: 1968 Coupe DeVille electrical issues
« Reply #4 on: September 09, 2017, 04:50:06 AM »
Hi Daniel

Welcome to the forum. I have attached the chassis wiring and the wiring connectors below.

I have a restoration blog where I post about my work on my 68 DeVille Convertible, check it out here: http://forums.cadillaclasalleclub.org/index.php?topic=130360.0

This post http://forums.cadillaclasalleclub.org/index.php?topic=130360.msg322626#msg322626 and this http://forums.cadillaclasalleclub.org/index.php?topic=130360.msg322669#msg322669 post cover the wiring behind the kick panel.

This one covers the ignition relay: http://forums.cadillaclasalleclub.org/index.php?topic=130360.msg322670#msg322670



Best regards,
Nicolas
« Last Edit: September 09, 2017, 04:53:31 AM by DeVille68 »
1968 Cadillac DeVille Convertible (silver pine green)

Offline BigggBender

  • Posts: 8
  • Name: Daniel Bender
Re: 1968 Coupe DeVille electrical issues
« Reply #5 on: September 12, 2017, 12:25:10 PM »
Thanks Nicolas, that's going to be really helpful.

I found the problem by now, the black/red main power cable got pinched a couple of inches from the starter. It and a bunch of other crusty 50 year old cables will be replaced soon.

Daniel

Offline Highwayman68

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Re: 1968 Coupe DeVille electrical issues
« Reply #6 on: September 12, 2017, 10:52:28 PM »
How are the rest of the wiring in the engine compartment? If you think that they need to be replaced too then it might be in your best interest to get a completely new wiring harness. I changed mine about 10 or so years ago. I have tried to find the receipt of where I bought it but I can seem to find one. I do have an email from that time for Rhode Island Wiring Services Inc (http://www.riwire.com/ might work) that I may have purchased it from.

Offline BigggBender

  • Posts: 8
  • Name: Daniel Bender
Re: 1968 Coupe DeVille electrical issues
« Reply #7 on: September 13, 2017, 12:38:28 PM »
Yes, I will probably have to replace the engine wiring harness, or at least all the wires running over or along the engine. Probably a good idea to just do them all.

I found one on jegs (http://www.jegs.com/i/Performance-Trends/759/23575/10002/-1?CAWELAID=230006180011417507&CAGPSPN=pla&CAAGID=44693592161&CATCI=pla-209602475111&catargetid=230006180039219818&cadevice=c&gclid=Cj0KCQjwi97NBRD1ARIsAPXVWWAOnIebQjt4g5IoVujIIzKUPKnniwNI3JYi0c-XKj89qZazdB4fVtYaAospEALw_wcB)

Anyone know if those are any good, or is there another source for an engine wiring harness?

Offline BigggBender

  • Posts: 8
  • Name: Daniel Bender
Re: 1968 Coupe DeVille electrical issues
« Reply #8 on: November 11, 2017, 01:13:00 PM »
Hi, me again,

maybe someone can help me real quick. The engine wiring harness finally arrived and is a perfect fit (via JEG's). But at some point someone replaced a relay on the firewall with a generic one. I'd like to go back to the original version, so I don't have to cut up the new wiring harness.

Can anybody tell me what relay this is exactly? I'm guessing blower motor, are there differences between A/C and non A/C cars?

It's the one sitting right below the vacuum switch.

Also while rewiring apparently my mechanic broke a switch on the transmission, that is connected to the engine wiring harness. Anyone have a guess what kind of switch that is?

Thanks!

Daniel
« Last Edit: November 11, 2017, 01:21:47 PM by BigggBender »

Offline Highwayman68

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Re: 1968 Coupe DeVille electrical issues
« Reply #9 on: November 11, 2017, 04:23:55 PM »

Can anybody tell me what relay this is exactly? I'm guessing blower motor, are there differences between A/C and non A/C cars? It's the one sitting right below the vacuum switch.
Pages 1-5 and 1-6 in the Shop Manual shows that you are probably referring to the Blower Relay. You can confirm by looking at the pictures on those pages

Also while rewiring apparently my mechanic broke a switch on the transmission, that is connected to the engine wiring harness. Anyone have a guess what kind of switch that is? If it is an Orange wire then that is for the Detent Solenoid inside of the transmission which is fed from the Downshift switch by the carburetor. See the wiring diagram in the shop manual starting on page 12-64.


Offline BigggBender

  • Posts: 8
  • Name: Daniel Bender
Re: 1968 Coupe DeVille electrical issues
« Reply #10 on: November 12, 2017, 10:42:03 AM »
Thanks for the quick reply! My Shop Manual is ordered and on its way hopefully.

Yes it's an orange wire. So if I understand correctly, the detent solenoid itself is inside the transmission, the part sticking out is just a connector and seal of sorts?

Thanks,


Daniel

Offline TJ Hopland

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Re: 1968 Coupe DeVille electrical issues
« Reply #11 on: November 12, 2017, 11:00:26 AM »
Yep.  that is just a plastic stopper with the terminal going through it.    There is another wire connected inside going to the actual solenoid which is also inside.     +12 on that terminal engages it which only happens at wide open throttle. 
StPaul/Mpls, MN USA

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Offline BigggBender

  • Posts: 8
  • Name: Daniel Bender
Re: 1968 Coupe DeVille electrical issues
« Reply #12 on: November 12, 2017, 01:38:40 PM »
Does that part have a name by any chance? I haven't seen how much it actually broke, but I might have to replace it.

Offline cadillacmike68

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Re: 1968 Coupe DeVille electrical issues
« Reply #13 on: November 12, 2017, 01:59:08 PM »
Is it a round connector, on the drivers side, maybe dime to nickel sized in diameter?
« Last Edit: November 12, 2017, 11:00:11 PM by cadillacmike68 »
Regards,
"Cadillac" Mike
Current:
1968 DeVille Convertible
1996 Fleetwood Brougham
2009 STS NorthStar Platinum ed RWD
2011 CTS PRemiun ed Sedan RWD
Past:
2008 CTS Premium ed Sedan AWD
2005 CTS Hi-Feature Sedan RWD
2000 ElDorado ESC Hard Boot Convertible
1995 Fleetwood Brougham
1973 Sedan DeVille
1970 Fleetwood Brougham
1969 DeVille Convertible

Offline BigggBender

  • Posts: 8
  • Name: Daniel Bender
Re: 1968 Coupe DeVille electrical issues
« Reply #14 on: November 12, 2017, 03:18:45 PM »
That sounds about right.