Author Topic: 1979 Eldorado no start...Ignition switch? Selnoid ? Relay?  (Read 203 times)

Offline nanaimogene

  • Posts: 43
  • Name: Gene McCormick
1979 Eldorado no start...Ignition switch? Selnoid ? Relay?
« on: October 09, 2017, 01:51:55 PM »
Before I jack the car up and bang the starter solenoid  with a hammer (worked on other cars) or clean the starter terminals I thought I ask you. Car has new battery,
Also before I pull the steering wheel and may replace the switch with new one (cheap on eBay). I turn the switch and hear the fuel pump come on , clock comes on
etc etc but no starter kicks in. Once I hit the steering column  with block of wood and it started..that was fluke. The shop manual shows a rod moving over to start mode sending juice to the starter solenoid.  With all those 4 relays in the fuse box ..any of those part of the starter circuit ?  By the way is there a way I can by pass the switch
to start the car so I can get it out of my gravel floor tent garage into my house garage.  Another brand  of car I owned and it had steering column switch with problems.
I miss my 2 57 Caddy's and 61 (now in Saudi Arabia) with dash mounted ignition switches. Any feedback appreciated. Gene
P.S. Once in my attempts to start the gas tank fuel pump would not shut off with switch off, had to unhook battery, Only happened once.

Offline Dave Shepherd

  • Posts: 1908
Re: 1979 Eldorado no start...Ignition switch? Selnoid ? Relay?
« Reply #1 on: October 09, 2017, 04:40:15 PM »
Jump the solenoid terminals on the starter, big cable to s terminal if it cranks you should check for 12 v to the solenoid in the crank position.

Offline "Cadillac Kid" Greg Surfas 15364

  • Posts: 2749
    • CLC Member
      CLC Member #15364
Re: 1979 Eldorado no start...Ignition switch? Selnoid ? Relay?
« Reply #2 on: October 09, 2017, 07:28:06 PM »
Gene,
I would check the Neutral Safety Switch located on the lower steering column. If this prooves okay than the issue MIGHT be with the ignition switch,  That wire rod goes from the lock to the switch and in the full clockwise position of the lock it is supposed to pull the ignition switch to the start position. Could be alignment of the ignition switvh or the switch could be bad or it could be the relay.  Need to start at one end of the chain and work to the end.
Greg Surfas
Cadillac Kid-Greg Surfas
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Offline bcroe

  • Posts: 2012
    • CLC Member
      CLC Member #14630
1979 Eldorado no start...Ignition switch? Selnoid ? Relay?
« Reply #3 on: October 09, 2017, 07:55:44 PM »
There is so much wiring in that car; in order to properly service it, you should have at least the
1979 CADILLAC SERVICE MANUAL, Cat No. S-1640. Another VERY USEFUL book is 1979
ELDORADO ELECTRICAL TROUBLESHOOTING MANUAL.

For maintaining 70s EFI cars I recommend having the blue & white book: CADILLAC ELECTRONIC
FUEL INJECTION DIAGNOSIS Manual 1099984 / S-1453. Its usually available on EBay, i have some
extra copies. Get a paper book, not a CD.  Bruce Roe, 79 ELDO owner

Offline nanaimogene

  • Posts: 43
  • Name: Gene McCormick
Re: 1979 Eldorado no start...Ignition switch? Selnoid ? Relay?
« Reply #4 on: October 09, 2017, 08:56:14 PM »
Thanks everybody...still working on it, Its not the solenoid  so far, will check rod alignment and neutral switch. Will get back to the club when problem solved.  Gene

Offline 35-709

  • Posts: 2743
  • The most valuable antique is an old friend.
    • CLC Member
      CLC Member #4719
  • Name: G. Newcombe
Re: 1979 Eldorado no start...Ignition switch? Selnoid ? Relay?
« Reply #5 on: October 09, 2017, 09:02:01 PM »
Also check the starter brushes.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold
1950 Jaguar Mark V Saloon resto-mod

Offline TJ Hopland

  • Posts: 6707
Re: 1979 Eldorado no start...Ignition switch? Selnoid ? Relay?
« Reply #6 on: October 10, 2017, 10:19:32 AM »
The key switch itself is on the right side of the column under the dash so its not that difficult to access.  There is a similar but smaller one on the left which is the highbeam.   Same general area on top is the neutral switch which in the Cads is a more common failure than the ignition.  The addition of the vacuum controls for the parking brake seems to make them a little more fragile.

Starter isn't too bad to do on these.   It bolts to the transmission with 3 bolts which is unique to this body style.   The solenoid is more likely to have issues than the starter itself especially from sitting in damp conditions.   Solenoid is common to many GMs and is easy to replace.   

Trying to remember is this car one of the first that has a starter relay near the fuse box?
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline bcroe

  • Posts: 2012
    • CLC Member
      CLC Member #14630
1979 Eldo no Crank
« Reply #7 on: October 10, 2017, 10:30:34 AM »
My book shows a single wire running from the ign switch to the starter
solenoid.  The switch is only allowed mechanically to turn in P or N. 

There are a couple fat single pin connectors in that big purple wire
which can fail, and a branch also goes to the ECU for fuel injection. 

Bruce Roe

Offline TJ Hopland

  • Posts: 6707
Re: 1979 Eldorado no start...Ignition switch? Selnoid ? Relay?
« Reply #8 on: October 10, 2017, 11:44:58 AM »
Its a mechanical interlock on the ignition switch itself?  Rather than the usual GM electrical via the neutral switch?  If so I have never had to work on one like that before.  Sounds like a place to have something get sticky with age. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline bcroe

  • Posts: 2012
    • CLC Member
      CLC Member #14630
Re: 1979 Eldorado no start...Ignition switch? Selnoid ? Relay?
« Reply #9 on: October 10, 2017, 11:50:41 AM »
Quote from: TJ Hopland
  Its a mechanical interlock on the ignition switch itself? 
Rather than the usual GM electrical via the neutral switch?   

Correct.  Bruce

Offline nanaimogene

  • Posts: 43
  • Name: Gene McCormick
Re: 1979 Eldorado no start...Ignition switch? Selnoid ? Relay? UPDATE
« Reply #10 on: October 12, 2017, 01:49:11 AM »
UPDATE  I did get the Eldorado's' started by bypassing the steering column ignition switch (basically hot wiring). The actuating rod does not move far enough to engage
the start contact. To get under dash safely doors should be wide open otherwise at my age I may get stuck there. Because of damp weather leave that job till spring. Keeping car  stock I will improvise by using trunk release yellow button with in line fuse and wire to starter solenoid. To start Step 1. Turn column switch to run position then push yellow button and presto car starts. Three years ago when I bought the Biarritz I noticed the heater was disconnected. Rather go through time consuming job
I decided to use the AC evaporator. It worked  well for chilly Canada. See pix. Even put on off on switch for summer driving. Thanks everybody for your suggestions. Love
Cadillacs. :) Gene

Offline TJ Hopland

  • Posts: 6707
Re: 1979 Eldorado no start...Ignition switch? Selnoid ? Relay?
« Reply #11 on: October 12, 2017, 07:44:12 AM »
The switch assembly has slots in its mounting holes that are used for adjustment.   If that doesn't do it then the only other thing I have seen is a problem with the little rack and pinion setup behind the key.  They sell repair kits for the mechanism. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline bcroe

  • Posts: 2012
    • CLC Member
      CLC Member #14630
1979 Eldorado no start
« Reply #12 on: October 12, 2017, 08:26:26 AM »
I checked 3 of my 77-79 cars and 2 of the wiring diagrams including the
79 Eldo; none of them used a starter inhibit switch on the steering column. 
The key isn't allowed to turn except in P or N.  However some other models
(Starfire) did have a switch, so its not universal then.  Bruce Roe

Offline TJ Hopland

  • Posts: 6707
Re: 1979 Eldorado no start...Ignition switch? Selnoid ? Relay?
« Reply #13 on: October 12, 2017, 08:50:22 AM »
I wonder if that inhibit mechanism is what is causing his to not move far enough?    Seems most likely.  Stiff grease?   Makes me want to go dig out a manual and see if there is a detail on that mechanism. 

The usual failure of the rack and pinion is the rack part cracks and breaks. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason