Wiring Issues

[markbob]

Hello,
had all my harnesses redone by Mr Heaterbox.....they also restored the heater/defroster controls....
I am just about finished with my 69 Coronet....and have a few issues....hoping you can help....
I cannot get my heater controls to work properly....
I checked the power coming to the heater controls unit off of the main harness today, by connecting a lighted testor to the wire, and jumping it to ground....the light did not illuminate....but I heard some clicking coming from under the dash....I thought it was a fuse....but all the fuses in the block behind the glovebox are ok....
I jumped the positive battery cable to the defroster/heater fan, and it runs....so it's not a fan issue....
The brake lights do not work either....tail lights work with the headlight switch...but no brake lights....
Lastly, I was wondering if you had any idea regarding a grounding strap that is attached to the right lug of the steering wheel mount....where does that attach to?
Everything is hooked up, except the connector to the steering wheel, since the wheel is not in yet.....]
thanks for the help....
Mark

 

[super-bee_ski]

Simple question but first off:
How is your ground?
Do an experiment.....
1. Run a known "good ground" to the box and re-check this first. (A Jumper)

 

[markbob]

Superbeeski,

I used a test light to check the voltage limiter for my gauges....it worked fine....
I used the same test light to check if there was power in the feed to the heater/defroster control....the light did not illuminate....
does this mean I have no power in the main harness?

U r saying to place a ground jumper on the actual panel in the dash?

plz advise....

thanks

Mark

 

[bandit]

That ground strap goes from one of the mounting bolts of the steering column to the mounting bracket. Helps ground the dash. You may see some issues clear up if you hook that up.

By any chance are your turn signals not working too? That cam in the steering wheel affects a lot of things when it goes including the brake lights. Make sure you have good grounds first though.

 

[markbob]

Bandit
thx for reply
i dont have steering wheel hooked up yet
wlll let u know how it goes once its hooked up
i used a test light and voltmeter to check temp sending unit
I have fluctuating voltage on voltmeter but not on test light
the fuel sending unit shows both
dont u love electrical?
Mark

 

[bandit]

The sending units for the fuel, temp and oil measure resistance so make sure you have your meter set to ohms for these. That is specifically to measure the sending units not the gauges themselves and you should have them unhooked from the gauges for the test to get an accurate reading. Basically one end of your meter goes to the wire coming out of the sending unit(you will have to start engine to get any reading out of temp or oil, but not for fuel) and the other to a good body ground. Do not test alternator gauge this way though. That one is measuring volts. All this said, I would not suspect the sending units at this point though.

If you are measuring at the back of your dash with everything hooked up you may see it bounce because of the voltage regulator. (rectangular piece plugged directly into back of dash cluster on circuit board). The voltage regulator basically takes 12v and reduces it to 5 volts for the dash cluster. (good idea to test this for 5 volts while you are back there) The way the old regulators worked is it bounced the voltage up and down to get an average of 5 volts. You will see this measurement bounce on your meter if you are measuring things back there. Best to use a meter with a needle and not digital. Digitals have a hard time seeing fast fluctuations. That clicking you hear may be the regulator clicking as it bounces and regulates the voltage but a bad ground may be why it is so loud. Those old ones are crude compared to todays solid state regulators(which some replace on their dashes for a more consistent voltage instead of the bounce).

Also, as far as gauges go, make sure you have the dash cluster screwed in fully to the dash or you set up a temporary ground if you are testing while it is not mounted. The dash cluster grounds through the actual mounting screws you screw in last after installing the gauges trim plate. Without the dash cluster mounted and screwed into the dash, you will get issues. In other words trying to test the cluster while unscrewed (which you have to do to get to anything to test) and not making a temporary ground may give you problems including with your wiper switch, light switch, etc.....

As far as the tail lights in back, I would not waste too much time on this until you get the steering installed and that strap hooked up. Plus I bet your power to the heater and tailights is being cut off because I suspect the main harness going into the steering column is not hooked up if you say you still need to install the steering.

 

[markbob]

Bandit,

will continue to work this....

I may not have been clear....but I used a test light on the wire leading to the fuel sending unit....it pulsed on and off....

I did the same thing with the temp sending unit wire....it does not pulse....
In my shop manual....it details how to test the voltage limiter in the car without removing it....
I did this, and get nothing....
It appears everything in my dash works....hazards....dash cluster lights....I suspect it's the sending unit....because I don't remember any issues with the dash instruments prior to disassembly....

will post a reply when I get steering column in....

thanks,

Mark

 

[Propwash]

Mark, what are you testing for with your fuel sending unit? Just to see if there is signal or to see it's giving the correct level, if any at all? A hot wire/volt test will tell you if there is a signal from the wire hooking to the terminal stud on the sending unit. An Ohms test will tell you if your sending unit is sending a signal and if it's the correct or at least a variance in fuel level to the gauge. To test that you would put one prod/clip of a micro/voltmeter on the stud of the sending unit that the wire hooks to and then ground the other clip/prod to the sending unit body. You would have to cycle the arm of the sending unit and should read from about 10-80/90 ohms when cycled from empty to full.

Like Bandit mentioned, your brake lights run through your turn signal switch. So, few things to check there......Bulbs, Grounds at/near bulbs, brake light switch (located near top of brake pedal with a pink & a white wire running to it) and also to insure the terminal connector from the turn signal switch is plugged into your harness. Your brake lights will not work if that is not plugged in. A bad dash voltage limiter will wreak Havoc on dash gauges as in bad readings or no reading at all.

 

[bandit]

Sounds like a grounding issue still. Did you test the limiter with a temporary ground wire attached to the cluster? You are losing a lot of ground when that dash cluster is out for testing.


Where approx are you at in the burbs?

 

[markbob]

I am in Batavia near Kirk Rd and Rte 56

my cluster is in.... I am going to do some more troubleshooting later
I put the trst light on my fuse block and the number two fuse has power in bottom but nothing on top
the number 6 fuse has no power either up or down

 

[bandit]

I am up near Wauconda, just north of Barrington.

On mine, 70 Charger, 4 and 5 are constant power and the rest are switched. I tested my number 6 too and am getting nothing, with key on or not. I looked up in my Charger book and #6 basically controls the dash and console lights and looks like it sources it's power from the dimmer switch. I do not have any of my dash lights hooked up yet(repairing a lot of what previous owner unhooked for aftermarket gauges) so probably explains it on mine.

All I can say about power at the bottom on #2 and none at top is look at the fuse or possible corroded connection. Nothing much in the way here except that.

 

[markbob]

Bandit....

I just ran some more tests....

I checked voltage limiter function at fuel tank sending unit with a test light.....I get a flashing light....

I checked voltage limiter function at temp sending unit with same light....I get nothing....
I placed a jumper wire from sending unit wire to ground.....temp gauge needle does not move....

I checked all wires behind dash....especially those leading to the round plug in center of instrument cluster....nothing seems amiss....

I checked wiring diagram....and the temp gauge and fuel gauge share feed from voltage limiter....

How is the cluster grounded? Is it through the dash itself? My headlights, instrument cluster lights, emergency flashers all work.
My steering wheel is not installed, so the harness connections to that are not hooked up....

if I place a jumper from the ground to the fuel gauge sending unit wire, and the fuel gauge needle moves, then does this mean I need a new temp gauge?

Any thoughts?

thanks,

Mark

 

[bigmanjbmopar]

Think I answered some of your items in another post, but as far as the brake lights go you have to have the steering column hooked up and grounded like bandit said. power for the brake lights routes through the turn signal cam in the column, also need to make sure your turn signal flasher is good as well as the hazard light flasher. if your cluster is loose in the dash screw it in or make a ground strap from the fram of the dash to the cluster for testing.

 

[markbob]

bimanjbmopar,

thanks for the reply....

I will be able to follow your advice when I get the steering column hooked up....
as far as the ground....if I jump a ground to the sending unit wire for the gas gauge, and the needle jumps, then is this indicative of a bad temp gauge?

when you say to ground the cluster, do I just jump the side of the cluster to a ground?

thanks,

Mark

 

[bigmanjbmopar]

Remember the gas gauge is a slow one and you would have to hold a ground on it for a 30 seconds or more to see it go full.

Coul be bad gauge or like I said in the other post check circuit board traces for open sections or broken pins on the clusters main connector.

Yes run a jump wire - make one with any wire you have and secure it to the frame of the dash and one of the mounting holes of the cluster then try testing every thing again.

Bad or improperly grounded equipment make up for around 90% of gauge and other electrical problems. I say it one more time GROUNDS! lol :headbang:

 

[PUNKN8R]

I have resolved my fuel gauge by finding out it was a
grounding issue therefore I simply took a 12 gauge wire stripped at both ends grounded one end to a good known ground and by touching other end to the fuel gauge limiter, Therefore I simply soldered the wire to the voltage limiter body and now I have a working fuel gauge.. Not saying this is your problem but might be worth a try ..... Good Luck !!!