Control indicators

[smily]

I have 71 Overlander, 27 feet.

I am working on my Control panel.
I changed all of the bulbs with new ones.

My holding tank indicators show, (lights on), both 1/2 and 4/4. I know that it is empty??????

My water tank indicates both, (lights on), 1/4 an 1/2 even when the tank is empty. The 0/0 indicator is not lighted.
When I depress the "holding tank" indicator switch, the indicator lights get even brighter.

My "Power on" light stays lighted even when the 120 volts is diconnected.

I am looking for help, maybe Andy will step in here.

Desperate,
Smily

[niftypkg]

Read my last post 'niftypkg.' Smily I might try cleaning the printed curcuit board. I found a short and a burned resistor, in mine. Possible that two adjacent soldered joints are shorting!! [after 30 ]years and possible water leaks. Look both sides. Also check that multi- terminal connector.

[smily]

How can I tell if any resistors are burnt. I have removed the PC baord and everything appears to be ok and no obvious burn marks.

smily

[niftypkg]

Smily, the resistor in my circuit was burnt out , nothing left. Didn't know the size so just put another small one in. Use a continuty tester[voltmeter ]and test.

[thenewkid64]

If the issue with the gauges is just the holding tanks you could also just have "Dirty Probes" Most tak levels are checked by a set of 4 probes that pass thru the tank wall and are immersed in the fluid in the tank. The current passing through the fluid it the tank to ground off the probe lights the light.

Ok, now that you have pictured it in your mind, say it with me . ECCKKK! If the probes are gooped up they will allow current to pass when there is no fluid in the tank. If you have a pin out of the connectors you may want to check the open/short status of the leads to the tanks before you tear the panel completly down.

[smily]

Thanks.
I cxan handle continuity and pinout but last night while re installing my control panel I made new discovery.

The fuse to the blue wire on my univolt, (Car battery + and circuit 5 as identified in ownwers manual), was blown. I did not have any voltage to the control panel due to the fuse being blown.

Apparently the blue wire supplies all voltage to the panel. My Owners manual indicates that the red and white wires are the trailer battery + and -. I have looked behind the panel and the wiring looks up to par but I cannot understand why there is no voltage between the red and white wires until they are back fed through the blue wire on the PC board.

I hope I am being clear and not confusing you.

Doea anyone know why all of the control panel voltage is coming from the blue wire which is parrallel to the Battery positive via the univolt. ( the blue wire is picking up voltage from the battery + at the univolt and backfeeding it to the control panel).

Is this correctly wired?

Smily

[thenewkid64]

Are all three colors at the control panel?

White, red and blue?

Or is the blue wire at the fuse panel on the univolt and the white and red are at the control panel?

After replacing the fuse does the panel work normally on any gauge?

As soon as you start looking at voltages that pass thru a printed circut board things can stop making sense. Many boards are multi layered, so you cannot really see where everything is connected.

[smily]

yes all three colors are present at the control panel via a multi pin connector behind the control panel.

I am certain that my PC board has only one layer because I can see every circuit and resistor connections on the board. It is somewhat primitive.

No the guages do not work properly which is what led me to working on the control panel.

I have posted a thread in the electrical section called control panel indicators that describes my guages and indicators.

Most of my guages stay on all of the time.

When I first opened the control panel I noticed that the PO had lifted all of the black wires from the bulbs off of the PC board and taped them up. Apparently the bulbs were staying on for quite some time and led to the butning of the bulbs.

Do you know if the panel is supposed to be fed from the blue wire which I believe is circuit 5. My owners manual does not indicate what is supposed to be fed on each circuit. It only indicates the fuse location on the univolt and applies circuit number to each fuse. circuits 1 through 5.

Smily

[thenewkid64]

I pulled out the servce manual for my MH to look at the control panel setup. I have gauges but the concept should be the same.

If I remember right did you say your Power on light stays on all of the time?

It sounds to me like you have a short to ground in the panel somewhere.

The service manual states that the power on indicator always has 12VDC present. The powering up of the univolt gives it a ground path and the light lights. In my manual the red wire off the wiring harness goes to the ammeter. The blue wire passes thru a small fuse on the panel and then becomes the common power for all gauges. This may be why you have a red and blue wire with 12 volts all the time.

All gauges are read by reading the voltage present on the tank probes this voltage is supplied by the panel when you push the switch. Voltage will always take the easiest path to gound (lazy stuff, huh?) If you have a short to ground in the panel that could be causing most of your troubles.

[smily]

I have two red wires at the control panel.

One red wire comes straight from the shunt at the Univolt to the ammeter. This wire does not go through the multi pin connector. There is 12 volts on this wire which is supplied from the shunt at the Univolt.

One red wire is through the harness which has a multi pin connector attached to it. there is no voltage on this wire

The multi pin connector from the harness interfaces with the control panel multi pin connector. The red wire at the multi pin connector from the control panel actually connects to the blue wire on the harness connector.

This does provide 12 volts to the fuse as you pointed out. This also agrees with the owners manual. why the colors change from blue to red is beyond me, never the less, there is twelve volts at the fuse and to the entire control panel.

I have looked closely at the PC board and I do not see any obvious shorts. I have lifeted all wires from the control panel and everything looks good.

I am trying to think where a short could exist that would close the circuit on all lights on the control panel. It is as if all of the switches are depressed,(which they are not). One thing that is strange is that when the holding tank switch is depressed, the indicators get even brighter than they already are, ( remember all lights stay on all of the time).


Confused,
Smily

[Jim Johnson]

Have a 73 Ambassador with the exact same problem you described - lights stay on and get brighter whenever you check level - did you determine what was causing your problem??
Jim J