Weird Lights

[j6mmer]

Hey, I'm new to this place so this may have been answered before, but I cannot find an answer.

 

So I think I have a bad ground somewhere on my '72 Monte.

 

Whenever I turn on a turn signal all tail lights and interior lights start flashing. The interior lights also illuminate when I apply the brakes. 

Headlights aren't affected though.

 

I've tried directly grounding the taillights to the battery, but it still happens. The body seems to be grounded alright and I'm totally clueless now.

My best guess is that there is something wrong in the dashboard area.

 

Is there a ground on the fuse box or bulkhead that could be bad because I can't seem find one?

 

Thanks

[monte70car]

Over time the 40+ year old wires will break down. Now it sounds like a ground issue, but the turn signals is it own circuit from the interior lights. Same with the brake lights. Does your interior lights come on when your headlights are on? And when you say interior lights are you talking about just the cluster lights or the dome and under dash lights? 

[stangeba]

 

 

I am not sure if you are talking about the dash lights or the dome light.

 

For the dash lights, yes there is a ground on the back of the cluster seen in these pics above. The dash ground wire attaches to the parking brake assembly also seen in a picture

 

 

If it's the dome light, my first thought is a pinched wire under the carpet or at the rear 1/4 panel. Did the car ever get hit?

 

Some have had problems with aftermarket or wrong headlight switches. Here is a picture of my 71 OEM switch.

 

 

 

[j6mmer]

@monte70car,

 

All of the interior lights turn on except the indicator and warning light come one when they're not supposed to. So when I use a turn signal for example the correct indicator light will illuminate properly and all other indicators (Gen, high beam, etc.) remain off like they are supposed to. However, the night lights for the radio and aftermarket gauges flash with the turn signal. The dome light doesn't have a bulb at the moment. 

 

The interior lights do come on with the headlights, but I have to adjust the turnknob for the lights all the way up before they come on. Also, when the headlights are on the turn signal no longer works at all. The light on the dashboard usually illuminates for the turn direction, but doesn't flash.

 

@stangeba,

Thanks for the pictures! I checked the ground wire on the ebrake and it seemed solid, but I will probably tear apart the dash and trace the wire to see if it's still in ok condition if I can't find any other solutions.

 

 

The previous owner left most of the wiring a complete mess. Most of what's in the engine bay has to be replaced because they got too excited with the wire cutters. Interior wiring seems pretty intact for the most part.

 

 

 

Thanks for the help!

[Rock]

Some times it's easier to start from square one which is what I did. I replaced my interior harness with an after market replacement. After 40+ years of after market stereos and gauges the wiring gets pretty hacked up. Luckily they make both the interior and engine bay harness for our cars. If you are feeling really motivated you can replace the idiot lights with gauges package which is what I did. When I bought my car the guy before me put a 20 amp slow blow breaker across the instrument fuse to hide a short in the wiring. Sometimes you have to wonder what goes on in some peoples heads.

[stangeba]

Don't forgot the ground wire on the back of the gauge housing on the far left (drivers) side at the lower edge, see second picture with arrow. The top or first picture also shows the ground strap thingy from the headlight switch. All grounds are critical!

 

The previous owner may have crossed some dash wires when he added the aftermarket gauges or the radio.

Try unhooking the wires for the illumination lights to the gauges, test it, then the wires for the illumination lights to the radio, if it's still messed up.

Many many times it's "what got changed" that is the cause of the problem!

 

Probably not an issue with your car, but trailer hitch wiring is a common source of electrical problems!

 

I once saw a person jam the wrong bulb into a socket, I think he forced an 1156 into an 1157 socket or the other way around, it was in the late 1960's!

 

Also bulbs made in China are smaller and don't fit tightly so they flicker.

 

Also I had a mechanic work (for a long time) on repairing both front parking lights not working, turned out to be TWO burnt out lights. (Not the brightest mechanic)

Good luck!

Bruce

[j6mmer]

@Rock,

I've considered breaking down and buying a whole new wiring harness, but they're a little pricey. However, I will have to buy a new one for the engine anyways, so I might as well spend a little extra and just redo everything.

 

@stangeba,

I took out the radio already. Surprisingly it was the original AM radio. I'm pretty sure it's shot though. I hooked it up to my test bench, but it just made a little crackle through a speaker and that was it.

 

I've been looking for every possible ground on this car, haha. I will check the ground you've pointed out the next time I can. It will probably be a few weeks, but I will give an update on if it worked or not if I don't forget.

 

Bad grounds will be the death of me. I have a 2002 Monte as well and I've had to fix 3 separate grounds in the last couple years. 

 

Thanks for the help so far!

[MCfan]

Dylan, I think you have a lot of company in your struggle with proper grounds. As you know, there are multiple grounds on our Montes' electrical system and having just one of them faulty can result in bizarre symptoms.

 

I certainly don't claim to know how to diagnose and repair complicated electrical circuit problems, but I recently experienced at least one of the symptoms you have described. My turn signals worked until I turned the headlights on, then they stopped working.

 

In checking all of the grounds I know about, I discovered the the only faulty ground was the screw that grounds the circuit panel to the back of the gauge housing - the one that Bruce already mentioned above. I know you plan to check it in the future, but I just wanted to mention that it is fairly easy to get to (by simply removing the dash pad) and tighten (or place a washer under it if the threads don't allow a snug fit to the circuit panel).

 

Be sure to first disconnect the battery. The first photo below shows the hex head screw on the back of the gauge cluster near the driver's end. The second photo was actually taken through the windshield with the cluster installed. There is ample room to get a small wrench (5/16" if I remember correctly) on that screw head and tighten it. If you need to install a metal washer under the screw head, that may be a bit more tricky but I'm sure it can be done.

 

I have installed so many additional electrical systems (AC, PW, keyless door/trunk locks, seat back releases, courtesy lights, HEI, etc) on my one '70 that I can't even imagine replacing the original harness but that may be a good fix in your case. Good luck.

[j6mmer]

@MCfan,

 

I definitely need to check that one! Along with many other things behind the dash...

Is there an instructional video or anything on how to remove the dash? 

 

The help from everyone has been phenomenal, thanks! 

[stangeba]

No video that I know of. 

To me the most important thing was / is to:

unhook the shift indicator wire or it will break! It's in my pictures above. 

I also would recommend a helper. 

Steering wheel being removed adds some needed space also.

Bruce

[j6mmer]

Found this gem... http://s1289.photobucket.com/user/psheean/media/MonteCarloDash_zpsf34e840a.mp4.html

 

Glad Chevrolet made videos like this.

[MCfan]

Thanks for sharing that video, Dylan. I had seen it before but couldn't remember when or where. Those instructions are good for completely removing the dash from the vehicle, however, it is not necessary to do that if all you want to do is remove the instrument cluster to work on the lights or replace the circuit board or gauges. However, you do need to completely loosen the dash so it can be pulled forward enough to remove the instrument cluster.

 

Following are some instructions posted by one of our members Tony (7tonemonte) some time ago that I have used:

 

I thought Id put these in here, a nice little "How to" for those removing their dash:

 

Just take your time and don't try to just force any part of it. The dash pods in our cars are VERY BRITTLE and will break if you just look at it wrong. Here is what I had to do:

1. UNHOOK BATTERY then Remove the dash pad

2. Unbolt two lower and three upper dash bolts (corners of the dash and near defrost vent) at this point the dash will be a bit easier to move but not even close to coming out.

3. I cut a 2x4 to use as a small wedge and removed the a/c duct above the climate controls and placed the wedge there to hold the dash out about 1 1/2 inches from normal. That is all I "needed" but would have gone a bit further knowing how tight it all was

4. Remove the headlight switch knob by pulling it out to the on position and pushing the button on the side of the switch mechanism and removing.

5. Remove the switch itself by removing retainer from the knob side. It can be unplugged and put to the side until the job is done.

6. Remove the small ground wire from the driver’s side of the rear of the gauge pod

7. Now you can remove the under column cover and then the screw on the lower side of the steering column that retains the gear selector wire and unhook the clip and leave it hang. **REMEMBER THIS IS THERE WHEN YOU REMOVE THE GAUGES OR YOU WILL BE MAKING EVEN MORE REPAIRS** (ask how I know)

8. While you are down there, remove the two bolts that hold the steering column in and support the column so it does not get bent.

9. Above the column, at the lower side of the gauges there are two 1/4 fasteners that need to be removed. They connect the gauge pod through two metal supports into the lower dash

10. Remove the three fasteners at the top of the dash pod (rear) and I believe two that are down the sides.

11. Remove the wire harness by depressing the clips on the sides and pulling it free, be careful not to rip the printed circuit, then if you have the factory clock remove the adjuster from the dash side with a small screwdriver

12. Pull the dash forward a bit and reach down the back and unhook the speedometer cable by pushing in the retainer and removing the cable

 

Your dash panel should now be free from anything holding it there, make sure I did not miss anything by looking carefully around the perimeter and you can now carefully guide the dash panel out of the dash. You may need an extra set of hands to keep wires out of the way when you get near the speedometer mount and don't forget you have that clip hanging at the bottom

[monte70car]

If you do go the route of a new harness American auto wire makes a nice kit for our cars, I have install one in both my 70 and my 72. Another item to add to Dennis steps is use machine bolts in the upper corner of the dash and you can slide the dash back on them.

[j6mmer]

Thanks for the detailed instructions Dennis! 

I will still probably remove the whole dash because I also have to work on the HVAC system.

 

Thanks for the further advice monte70car. I took a look at American Auto Wire and they do look pretty good. Were your installs pretty straight forward? By that I mean did you have to add any extra connectors or cut a lot of wires to length? I do a lot of electrical work so I'm not afraid of doing my own wires, but I'd rather not, haha.

 

I'll try to upload some pictures so you can see what I have to work with. 

 

Is there another way to post pics without using a URL?

 

 

http://s1078.photobucket.com/user/j6mmer/media/074_zpsv3cplf7a.jpg.html?sort=3&o=212

[monte70car]

Dylan to post a picture instead of the URL put the following before the URL and after the URL [i m g] (picture URL here) [/ i m g] but put the img and the /img together with no spaces.

 

As for the harness the wires are left long so you can route the wires how you like. You do have to add the needs to the wires once you have them where you want them. This is a few of the install on my 70 updated fuse box with the newer fuses. originial fuse panel which shows all the extra wires running to it. The new one as a power option plug that has its own connection outside the fuse box. new horn relay which is inside the car behind the cluster. gauge cluster connection (can be used with a stock cluster or aftermarket system.) The 70 I reused the original tail light sockets as the stock rear light harness is on unit for the tail lights, backup lights, tag light and the fuel gauge. On my 72 I used the AAW tail light socket setup and ran each wire to it's location.

[j6mmer]

Thanks monte70car, going with a whole new wiring harness looks like it would be a much better option in the long run.

[j6mmer]

UPDATE:

 

I took the dashboard apart and found A LOT of rats nest. It looks like they did a number back there and I'm kinda surprised anything works. 

It looks like I will be needing a whole new wiring harness 

 

Thanks for all the help and suggestions though! 

[Rock]

40+ years of adding aftermarket stuff tends to do that to a wire harness when amateurs wire the stuff in. Mine was a mess too but I was able to repair it and in the process pulled about 60 ft of wiring that did not belong.

[j6mmer]

@Rock,

 

That it does! My problem extends to more than just the wires...the PCB behind the gauges has seen better days. 

Fortunately I plan on replacing most of the interior wiring and doing more custom work. It would just be nice if I could use the turn signals, haha.