Author Topic: Interior Lights Only Work When Key is Turned - 68 DeVille  (Read 635 times)

Offline Bentley

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Interior Lights Only Work When Key is Turned - 68 DeVille
« on: November 29, 2017, 06:31:31 PM »
Hello,

When I open the door, the interior lights do not go on until I insert the key and turn to either the accessory or on positions. Same thing for the glove box light and the trunk light. Also, the presets on the aftermarket stereo get deleted each time I shut the car off. The body shop was the last place that worked on it, so they must have done something. I picked it up from them last summer, and didn't notice it until now that the days are shorter. Any ideas on what may be causing this?

Thanks,
Wes
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Offline Glen

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Re: Interior Lights Only Work When Key is Turned - 68 DeVille
« Reply #1 on: November 30, 2017, 12:04:51 AM »
Sounds like the car has been rewired.  Maybe a past owner had a battery drain problem and this was his fix. 
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Offline m-mman

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Re: Interior Lights Only Work When Key is Turned - 68 DeVille
« Reply #2 on: November 30, 2017, 03:32:31 PM »
A car's electrical system is divided into two general parts. Things that get power when the key is on (run or accessory) and things that get power all the time. (interior lights, trunk lights, clock)

The back of the key of course gets power all the time and then sends it out when it is switched on. Not sure about 1968 but commonly the fuse box has two separate areas. One that is powered all the time and one that is key activated.

An aftermarket electronic radio has TWO power wires. one that should get power all the time (to maintain the clock and presets) and one that is keyed. (powers the tuner and amplifier)

As mentioned above someone has moved the connections to the wrong places.
There is no way to diagnosis it without tracing the wires (and fuses) to see what it powered when and then putting things back to the way they should be.
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Offline TJ Hopland

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Re: Interior Lights Only Work When Key is Turned - 68 DeVille
« Reply #3 on: November 30, 2017, 05:05:35 PM »
I too am not sure how they were doing it in 68 but slightly later there were 3 fusible links on the starter battery terminal.    One to the headlight switch, one to the key which then fed half the fuse box, and one to the rest of the fuse box for the stuff. 

I wonder if the fuse box link blew or was damaged and something is back feeding that side from the key side?   With aftermarket stereo we know there was at least some rewiring going on.  Its also possible that a back feed jumper was installed as the 'fix' when the link was damaged whenever or whoever that happened.   
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Offline Bentley

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Re: Interior Lights Only Work When Key is Turned - 68 DeVille
« Reply #4 on: December 05, 2017, 03:04:00 PM »
Thanks for your help, everyone. I'm working on it.
Wes Bentley
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Offline Highwayman68

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Re: Interior Lights Only Work When Key is Turned - 68 DeVille
« Reply #5 on: December 05, 2017, 05:22:34 PM »
Hi Bentley,

Do you have a Shop manual? I like to provide page references to help make the answers easier.

Just a quick test, try the horn with the key not in, if it doesn't work that will mean most likely the "Constant On" power section is incorrectly fed.

Remove the fuse panel as described on page 12-50 by pulling the spring lever on the left of the fuse block and let it fall down.
Look at the page appropriate for your model 12-65, 12-67 or 12-69. You will see that the fuse block is divided in to 3 sections based on when power is to be applied to each section. 

The interior lights, glove box light and the trunk light are all fed from the same constant power source at the bottom of the fuse block (The factory radio is in the section fed with the key 'on'). Verify that the fuse for "CLK-LTR Body" is being fed from the section with the #10 B/R wire.

If this all looks good then trace the #10 B/R wire to verify that it is connected continuously to the constant source terminal on the starter.

Offline TJ Hopland

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Re: Interior Lights Only Work When Key is Turned - 68 DeVille
« Reply #6 on: December 05, 2017, 08:01:39 PM »
Is it the 3 fusible link from the starter scheme they used in the 70's?
StPaul/Mpls, MN USA

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Offline Highwayman68

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Re: Interior Lights Only Work When Key is Turned - 68 DeVille
« Reply #7 on: December 06, 2017, 10:57:20 AM »
Is it the 3 fusible link from the starter scheme they used in the 70's?

Yes, there is a 18DG and two 16B wires connected to the Starter.

Offline Bentley

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Re: Interior Lights Only Work When Key is Turned - 68 DeVille
« Reply #8 on: December 27, 2017, 06:29:00 PM »
Mike,

Thanks for your help. I got busy with work right before holidays, and now I finally have some time off. I'll pull the fuse block and check the fuse and wire as you instructed, and get back to you.

Thanks,

Wes
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Offline Bentley

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Re: Interior Lights Only Work When Key is Turned - 68 DeVille
« Reply #9 on: December 30, 2017, 06:11:20 PM »
I finally got some time to look at the car. The weather has been nice here, so of course I had to put the top down and drive it first.

First I tried the horn without the key in. It didn't work. Next I dropped the fuse block. All fuses are good. The wire that connects to the fuse CLK-LTR Body is the orange wire, and according to the shop manual, p.12-65, that is the correct wire. But something doesn't look right with the back of the fuse block. See attached photo. It looks like someone jumped a blk/red wire from the bottom of the fuse block (Stop/Hazard terminal) to the center. According to the wiring diagram, this small blk/red wire should not be there.

If the fuse block is correct, the next step is to look at the fuseable link at the starter. How far away from the starter is it? What do I look for? And if it is blown, does anyone know of a good source for a replacement?

Thanks,

Wes
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Offline TJ Hopland

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Re: Interior Lights Only Work When Key is Turned - 68 DeVille
« Reply #10 on: December 31, 2017, 06:59:01 AM »
It would kinda fit from what you describe that someone jumped the sections together possibly due to a blown link wire. 

Typical for GM is a 5 wire harness down to the starter.  2 standard wires go to small the small terminals, one is for the coil bypass and the other to engage the starter.   The other 3 wires go to a single large lug which is on the fat battery terminal.   Those 3 are the fusible link wires and have a different softer more soft rubber insulation and are solid wire so they feel different if you flex them.    One feeds the headlight switch,  one fuse box for stuff that is always live (your problem area) and the last one feeds the key that then the rest of the fuse box.   It seems like in your case someone jumped the key on section to the always on section.   Perhaps that black/red wire is cut?  And that eventually leads to the starter?

Typical length is 12"-18" and then you will see a connector or splice back to regular harness wire.   When they 'blow' the internal wire basically melts like a fuse but the insulation is supposed to stay in tact so if you can feel the wire you can usually feel where the break is. 

For newer or more popular stuff you can often buy pre made new harnesses.  For this you may have to make it yourself.   The link wire is available at parts stores and I'm sure online.   I bought some at Napa and I think it came on like a 15' roll in a little package.   Its based on wire gauge size.   Typically 4 sizes smaller than the wire its protecting and in this case they count all the numbers, not just sizes that are available.   So if the main feed wire was a #10 you would use a #14 fusible link wire.   For length just duplicate what was there.   The last car I had to do it on was a 73 Cad which had a 6 pin connector in the harness so it was link wire from the big terminal to the connector.  At the time I didn't have new connector pins so I cut the damaged wire an inch or so from the connector and soldered then heat shrink the new wire on.    If you can't tell by looking at the harness the diagram usually has some way of identifying the wire size.
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75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline Highwayman68

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Re: Interior Lights Only Work When Key is Turned - 68 DeVille
« Reply #11 on: December 31, 2017, 10:59:50 AM »
Agreed, the fuse link near the starter probably blew and either the person fixing the issue didn't know where to look or didn't want to replace the blown fuse link so they did the next best thing in their mind and made a jumper to the closest source of power being the Key supply.

Check the wire from the terminal on the starter to the fuse link, if soft or melted replace the fused link (Available at Napa).

You may also find the wire from the the starter could have melted against the engine block and shorted requiring the entire wire to be replaced.

Look around the area under the dash where the fuse block sit and look for the #10 Black with a Red strip wire that should be feeding that section of the fuse block, it may be just cut off or taped up.

Eventually you will need to a continuous run from the starter to the fuse block to get this corrected.
« Last Edit: December 31, 2017, 11:17:49 AM by Highwayman68 »

Offline TJ Hopland

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Re: Interior Lights Only Work When Key is Turned - 68 DeVille
« Reply #12 on: December 31, 2017, 07:30:16 PM »
I bet its cut since the odd looking jumper is black/red.   They clipped it and crimped that new end on to jump it to something that worked.
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 Bentley

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Re: Interior Lights Only Work When Key is Turned - 68 DeVille
« Reply #13 on: January 04, 2018, 03:45:18 PM »
Mark and TJ,

Thanks for your explanations and comments. They have been a huge help. After reading your last comments, I pulled the fuse block down again and searched for the black/red wire. I found it coming out of the harness, where someone had cut it and reconnected it via a yellow crimp connector and some tape. See photo # 2508. This is a view from behind the fuse block.

Then, they connected it to a yellowish-greenish wire via a blue crimp connector. See photo # 2509. This yellowish-greenish wire goes up and over the yellow wire and down to the left, where it terminates in the lower left corner of the fuse block. Do either of you have any idea why they would do this?

I haven't checked the fuseable link yet because I need to get the car to my mechanic to put it up on the lift, so we can see under it. I'll post again once we do that.

Thanks again for your help.

-Wes
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Offline DeVille68

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Re: Interior Lights Only Work When Key is Turned - 68 DeVille
« Reply #14 on: January 13, 2018, 01:54:58 AM »
So, it is a bit difficult to identify the exact terminal the wire leaves from. However, from my wiring diagram I only see two wires that could be feasible. They are 18DG, one goes to the body connector (to the rear marker lamps), and the other goes to the light switch (terminal 4).

So, to me it seems that there must be another problem. The interior lights are supplied with power by the 25 AMP CLK-LTP-Body Fuse. The 10 B/R Wire goes to the battery terminal on the starter solenoid. But first through a fusible link. At the start of the fusible link a 12OR splits off and it goes to the blower relay.
So check that those two wires have power all the time.

I am guessing that someone messed with your harness going or coming from the starter solenoid.
On my 68 DeVille someone also messed with these wires and removed all fusible links and made some none original connections.

Do you have a wiring diagram?
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Offline Highwayman68

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Re: Interior Lights Only Work When Key is Turned - 68 DeVille
« Reply #15 on: January 13, 2018, 08:22:12 AM »
Sorry I missed your January 4th posting.

Here is another test to try, without having the key in see if your Hazard lights work. I believe that it will work.

What I am thinking from what I see in the pictures is the constant power was removed from the feeder terminal on the fuse block because the battery kept going dead while the car was sitting and replaced with the short jumper wire now in place that provides power only when the car is running and charging the battery. They may have found that the interior lights were staying on when the car was sitting and rather than fix the source of the issue they changed it so that power was available only when the car was running. But they realized that they couldn't have the Hazard lights working only with the key in the car so they rewired it through the wire crimps you found to keep constant power to the Hazard terminal on the fuse block.

If all of this is true then the next test to try is to reconnect constant power to the feeder terminal and let the car sit for a several days and see if the battery starts to loose it's charge. If it does we can look at how to address that issue.

Offline bcroe

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Interior Lights Only Work When Key is Turned - 68 DeVille
« Reply #16 on: January 13, 2018, 11:31:43 AM »
Letting a battery sit for some time in a discharged condition is about the
worst thing you can do to it.  And if its cold enough it will freeze for
total destruction. 

If there is doubt about a constant drain, connect a small 12V bulb between
a battery terminal and its cable.  A small (193) bulb should not light at all,
otherwise track down the drain.  Meanwhile either have a substantial battery
maintainer connected or disconnect the battery.  Bruce Roe
« Last Edit: January 18, 2018, 08:30:14 PM by bcroe »

Offline Bentley

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Re: Interior Lights Only Work When Key is Turned - 68 DeVille
« Reply #17 on: January 18, 2018, 07:37:38 PM »
Nicolas,

I have the shop manual and I downloaded the PDF files of the wiring diagram you posted. I printed it on large paper. When I was first looking at it, I thought, that's cool, they had a font that looked like handwriting back then. Then I realized, they didn't even have computers back then. The entire diagram was drawn by hand! It's remarkable the level of skill in drawing and lettering the engineers and draftsmen had back then.

I had to take the car to my mechanic to put it up on the lift to check the fusible link from underneath. I'll also check the 12OR wire to the blower relay as you suggested. Thanks.

Mark,

I'll do the hazard light test you suggested. After the constant power wire is connected to the correct terminal, I'll do the battery charge test.

Bruce,

If it fails the charge test above, I'll do the light bulb test.


Thanks for your help,

Wes
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Offline DeVille68

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Re: Interior Lights Only Work When Key is Turned - 68 DeVille
« Reply #18 on: January 22, 2018, 03:31:11 AM »
ok, let me know if you need some more scan. I have all the drawings in pdf
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Offline Bentley

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Re: Interior Lights Only Work When Key is Turned - 68 DeVille
« Reply #19 on: January 31, 2018, 07:01:43 PM »
Hello All,

I'm getting back to you to let you know how this story ends. I brought the car to my mechanic. The fusible link in the Blk/Red wire from the starter was okay. So he traced the Blk/Red wire to the junction box (I'm not sure what it's called) in the firewall. See photo #2539. Then he looked at the terminal that connects this wire to the box. The terminal was fried. See photo # 2542. The terminal on the left came out of the car. The one on the right is what it should look like. So he fixed that. Then he removed the jumper wire on the fuse block. Remember that was the one that jumped from the ignition to the CLK-LTR as a way to supply power to interior lights. And that solved the problem. Thanks for all of your help.

Wes

P.S. I complained to the body shop that caused this problem and they agreed to reimburse me for the cost of this repair.
Wes Bentley
CLC # 30183

 

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