Author Topic: 1970 Deville - Parking lights come on when brake pedal pressed  (Read 275 times)

Offline grantatx

  • Posts: 30
  • Name: G. Scanlen
1970 Deville - Parking lights come on when brake pedal pressed
« on: October 03, 2017, 10:31:37 PM »
Hi all,

I've got one more issue to sort before I can get my car inspected - the front parking lights come on when I press the brake pedal. I've done a lot of searching on this forum and elsewhere, also looked at an online copy of the wiring diagram and everything seems to point to a faulty turn signal switch. All other lights work fine. I don't have a great knowledge of electrical troubleshooting so (rightly or wrongly) I figured the best idea would be to just replace the switch and see if it fixed the problem. The turn signal switch is the only place I can see on the wiring diagram that both circuits meet. Anyway, I purchased a repro switch from OPGI and have the column stripped to the point where I'm trying to get the switch out of the column, which is proving very difficult. So I have two questions:

1) Has anyone had the same issue, and how did you fix it

2) Has anyone replaced a turn signal switch and if so how did you remove the switch from the column?

Thanks again in advance.

Grant

Offline TJ Hopland

  • Posts: 6823
Re: 1970 Deville - Parking lights come on when brake pedal pressed
« Reply #1 on: October 03, 2017, 10:46:14 PM »
Have you checked all the bulbs?  Maybe somehow a single contact got stuck in a double socket or the wrong double is installed somewhere?    Ground issues are good at making just one light act fully.
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 grantatx

  • Posts: 30
  • Name: G. Scanlen
Re: 1970 Deville - Parking lights come on when brake pedal pressed
« Reply #2 on: October 03, 2017, 10:56:20 PM »
I did check that all the lights worked, but I haven't pulled all the bulbs. I'll do that tomorrow, thanks!

Offline TJ Hopland

  • Posts: 6823
Re: 1970 Deville - Parking lights come on when brake pedal pressed
« Reply #3 on: October 03, 2017, 11:02:48 PM »
It may not be the one that is acting up that is wrong or has the ground issue.  Check every lamp and socket involved in the brake and parking lights.    Just taking them all apart to check them may solve the problem if its a ground or contact issue.
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 Glen

  • Posts: 2270
    • CLC Member
      CLC Member #727
  • Name: Glen Houlton
Re: 1970 Deville - Parking lights come on when brake pedal pressed
« Reply #4 on: October 04, 2017, 01:25:27 AM »
Is it the front parking lights that come on or the front turn signals that come on?  Makes a difference. 
Glen Houlton CLC #727 
CLCMRC benefactor #104

Offline Jeff Rose CLC #28373

  • Posts: 1431
  • Name: Jeff Rose
Re: 1970 Deville - Parking lights come on when brake pedal pressed
« Reply #5 on: October 04, 2017, 06:34:11 AM »
You can also just unplug the turn signal switch at the base of the column to test your theory.
Jeff
Jeff
CLC #28373
1970 Coupe DeVille
1955 Series 62

Offline klinebau

  • Posts: 13
  • Name: Kurt Linebaugh
Re: 1970 Deville - Parking lights come on when brake pedal pressed
« Reply #6 on: October 04, 2017, 07:36:59 AM »
Replacing the turn signal switch is a PITA.  You have to remove the steering wheel lock mechanism and remove the turn signal stalk.  You also have to remove the emergency flasher knob and don't lose the piece that the flasher mounts to inside the column.  After that, you must disconnect the "harmonica" connector and loosen the bolts for the steering column.  Make sure that you note where the shims are located as they will likely fall out.  Finally, you need to remove the turn signal wires from the sleeve under the steering column.  After that, you will be able to pull out the turn signal switch and the harmonica connector, but it is still a tight fit.  The factory service manual spells this out in more detail.

After you have the old switch out, make sure you compare the new harmonica connector with the old one.  I had to swap all of the wires from the new connector to use the old connector as the new connector did not fit.
1970 Cadillac Deville Convertible
Detroit, MI

Offline grantatx

  • Posts: 30
  • Name: G. Scanlen
Re: 1970 Deville - Parking lights come on when brake pedal pressed
« Reply #7 on: October 04, 2017, 08:13:20 AM »
Thanks for all the responses guys! I've already disassembled the steering column to the point I can get the switch out but am going to stop and first check all bulbs and circuits as you've suggested.

Jeff, I'll try your suggestion of disconnecting the switch under the dash, however from what I can see the brake light circuit goes through the switch on the way to the rear of the car, so if I disconnect it they won't work will they? Forgive my lack of knowledge of car electrics - I'm learning as I go!

Thanks !

Grant

Offline grantatx

  • Posts: 30
  • Name: G. Scanlen
Re: 1970 Deville - Parking lights come on when brake pedal pressed
« Reply #8 on: October 04, 2017, 05:31:44 PM »
A quick update - I've checked all the bulbs and everything seems to be in order. However, while doing so I noted the following:

1) When the brake lights are on it is the parking lights that are on in front, but quite dimly

2) With the brake lights on and the front indicator flashing, the parking light filament also flashes very dimly. Even when I take the light socket right out of the fitting so it's not earthed.

I've printed off the wiring diagram for a more detailed analysis but if anyone has any further suggestions I'd appreciate them!

Cheers,

Grant

Offline grantatx

  • Posts: 30
  • Name: G. Scanlen
Re: 1970 Deville - Parking lights come on when brake pedal pressed
« Reply #9 on: October 04, 2017, 05:47:04 PM »
Oh, and:

3) Front marker lights come on when brake lights are on also

Offline grantatx

  • Posts: 30
  • Name: G. Scanlen
Re: 1970 Deville - Parking lights come on when brake pedal pressed
« Reply #10 on: October 04, 2017, 06:53:27 PM »
Right, I think I know where the problem is. The rear side marker lights are coming on when the brake pedal is pushed, and I don't believe they should. According to the car manual and the workshop manual they should only come on when the headlamp switch is either halfway or fully on. Please can someone confirm I'm correct on this?

Thanks very much!

Grant

Offline Jeff Rose CLC #28373

  • Posts: 1431
  • Name: Jeff Rose
Re: 1970 Deville - Parking lights come on when brake pedal pressed
« Reply #11 on: October 04, 2017, 06:58:49 PM »
Have you tried it with the bulbs removed? You must have circuits crossing somewhere. Most likely the rear bulb sockets. If you remove bulbs and the problem goes away then that gives you something to work with.
Remove all rear bulbs and hit the brake. Do you still have the problem, etc.
Jeff
CLC #28373
1970 Coupe DeVille
1955 Series 62

Offline TJ Hopland

  • Posts: 6823
Re: 1970 Deville - Parking lights come on when brake pedal pressed
« Reply #12 on: October 04, 2017, 07:22:36 PM »
Any signs that there was ever a trailer hitch installed?   Trailer light connector?   Look around the rear for any signs that the harness has been messed with.  Where trailer lights were spliced in is one of the best places to find issues.

 
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 grantatx

  • Posts: 30
  • Name: G. Scanlen
Re: 1970 Deville - Parking lights come on when brake pedal pressed
« Reply #13 on: October 04, 2017, 09:28:54 PM »
Jeff, you're 100% correct, it was one of the bulb sockets! Thank you!

Now the question is, how do I fix it? Are they a commonly available part? Guess I'll consult Google :-)

Offline chrisntam

  • Posts: 1279
  • Dallas, Texas
    • CLC Member
      CLC Member #29206
  • Name: C. Jessen
Re: 1970 Deville - Parking lights come on when brake pedal pressed
« Reply #14 on: October 05, 2017, 03:49:30 AM »
Rock auto may have them.

www.rockauto.com

1970 Deville Convertible  MTS 507
Dallas, Texas

Offline grantatx

  • Posts: 30
  • Name: G. Scanlen
Re: 1970 Deville - Parking lights come on when brake pedal pressed
« Reply #15 on: October 05, 2017, 08:48:41 PM »
Update: I got a replacement socket from O'Reilly, cut the old one off and tested with the new socket. The problem was still there! Believe it or not, it was the bulb that was causing the problem. A new $2 1157 bulb fixed it.

 

Get the CLCMRC 2018 Calendar - AVAILABLE NOW!