2001 Back-Up lights on all the time

[int3man]

Hi All,

            Well is shouldn't be this hard, but it wants to be.  Got up and headed for the airport at 3:30 A.M.  Noticed the Truck reverse lights were on.  Went back and got the keys and cycled the shifter. No difference.  Got back this morning and replaced the Neutral safety switch and Reverse light switch.  So reading the linkage adjustment page, I can see nothing wrong.  The truck starts in Neutral and Park only.  So why are the Back-up lights still on 24 / 7, with a new switch????

 

I metered the voltage it's a solid 12 volts.

 

Any suggestions?  Only thing that I can think of is the wires have rubbed through?  Gremlins

TIA

Michael

Edited March 30, 2019 by int3man

[int3man]

Well while mowing the lawn I had a thought.  The P.O. installed L.E.D. bulbs everywhere.  So that said I noticed that there was oil in the Neutral safety switch plug.  So the oil maybe leaking enough Milliamps that allow the L.E.D.'s to light up?  So it's like CMOS and I need a Pull up, or pull down resistor.  So put a 1/ 4 watt 10K across the bulbs to pull the floating voltage down?

 

Or just install a pair of 3157 and call it even.

 

Your thoughts?

TIA

Michael

Edited March 31, 2019 by int3man

[Mopar1973Man]

3 hours ago, int3man said:

I metered the voltage it's a solid 12 volts.

 

The switch on the transmission is bad.

 

 

[int3man]

42 minutes ago, Mopar1973Man said:

 

The switch on the transmission is bad.

 

 

I replaced the switch on the transmission.  I'll meter it out tomorrow.  Bought one at ORiley's. I was lucky and a Snap on 1" Socket just fit it.

 

Back in the day we used to pull the CMOS input high (+5Volt) with a 10K ohm resistor so they didn't react to noise and stray signals.  The oil might be enough of a conductor to cause them to light, conducting milliamps at 11 volts.  I've got a resistor laying around somewhere and Test it tomorrow.

 

I'll let you know tomorrow.

 

Michael

[Mopar1973Man]

I'm going to bet it still the switch is bad. Power should not be present at the light socket. Switch should be open with no power. I would ohm test across the pins of the switch. 

[int3man]

Well it's funny you should say that I showed the kid at ORiely's that the "New" switch looked like it was used or had been installed.  So I have the old one out to test.  Next time I'll have the truck pointed downhill lost about 2 quarts of oil.

 

Thanks again

Michael

[Mopar1973Man]

3 minutes ago, int3man said:

Next time I'll have the truck pointed downhill lost about 2 quarts of oil.

 

You could drive up on some blocks of wood or ramps and raise that side of the truck. Even a road ditch will work. A quick swap and be done.

[int3man]

6 minutes ago, Mopar1973Man said:

 

You could drive up on some blocks of wood or ramps and raise that side of the truck. Even a road ditch will work. A quick swap and be done.

Great Idea.  Thanks!

 

Looking at the color of the Trans Fluid, I'm going to have the Trans Fluid and filters changed and the Bands adjusted.

 

Michael

Edited March 31, 2019 by int3man

[Mopar1973Man]

You are welcome... 

[int3man]

O.K. So it is a parasitic Voltage coming from the reverse light switch.  I got everything retested today and Still had 11 volts with the truck in park, at the reverse lights.  So I left the L.E.D. in one side lightly glowing and then I put and 3157 in the other side and the L.E.D. went out.  So the bulb had enough resistance to take the voltage to nothing.  The Transmission fluid in the reverse light switch has enough conductivity to conduct voltage but at a milliamp level (Volume) , enough to light a L.E.D. but not a light bulb.  So if I wanted to run L.E.D.'s I would have to run with a resistor in Parallel with the bulb?  A Question for IBMobile perhaps.  P= IxE and E/ (Ix R) and all that.

 

TIA 

Michael

[IBMobile]

16 hours ago, int3man said:

So if I wanted to run L.E.D.'s I would have to run with a resistor in Parallel with the bulb?

 

Two ways you could fix the problem, that I can think of, with out going through all the volt, ohm, amp calculations.

The first way is to put a resistor in parallel with the back-up lights to mimic a light blub and absorb that leaking power as you suggested above.

The other way is to put a relay in the back-up light circuit this would keep any power from going to the lights until the back-up switch is closed.

 

If a resistor was put in series either before or after the led blub then the blubs would be dimmed. 

 

 

 

Edited April 1, 2019 by IBMobile

[Mopar1973Man]

I still say switch is bad. Positive 12 volts will not jump a gap in ATF. I can see if the switch was ground and bleed being the entire transmission is ground. But +12V is not going to jump ATF and only to the reverse light. At any point electricity takes the easy path not one with resistance.

[kzimmer]

10 hours ago, Mopar1973Man said:

Positive 12 volts will not jump a gap in ATF.

Agreed. Oil is an electrical insulator. It would arc through an air gap before it would through oil. Oil filled transformers rely on this.

Edited April 1, 2019 by kzimmer
More useless information

[int3man]

Well I guess when the truck gets back from the headliner replace I'll drop the new switch out and meter it.  But when I installed a 3157 the L.E.D. Bulb went out.  Just saying.  So right now there are no Back up lights on.  It has a 3157 and an L.E.D. Bulb installed.  Remove the 3157 and the LED will light.  So if the switch was bad the 3157 should be lit correct?  Boy turns out this is a good question.  IBMobile want to weigh in?

 

Transformers still use insulated wires, other wise the length of wire in the winding would be length 0.  The insulated wire is what allows the wire to be wound and to have length and create the electromagnetic field.  The oil is to dissipate the heat.

[Mopar1973Man]

Again simple. Just unplug the switch and see if the lights go out. If so the switch is bad. Pure and simple. 3157 bulb is not getting enough to light but still running current. LEDs just take much less current to light up. Since the switch is either open or close it seem the contact is lightly being pressed. Is the shift selector slightly out of adjustment?

[kzimmer]

4 hours ago, int3man said:

The oil is to dissipate the heat.

 

Half right half wrong. Yes the windings are insulated. The oil does dissipate heat, but it most definitely insulates against arcing. If you don't believe me, drain one, stand back, and fire it up. This almost happened to one of our 13.8kv to 480v transformers. This is especially important with higher voltages, and is why larger transformers trip and lock out if they sense low oil.

 

I might have missed this, but further to Mike's comment about the shift selector adjustment, are the reverse lights on if you pull the lever all the way to '1'?

 

My vote is a high resistance short in the switch contact when it is supposed to be open. However, let me be lazy for a moment, because I don't want to look at the drawing, but does this switch +12v or does it switch ground? I'll look for myself when I have more time. 

Edited April 1, 2019 by kzimmer
Addition

[IBMobile]

3 hours ago, int3man said:

 Boy turns out this is a good question.  IBMobile want to weigh in?

NO!   But, check your switch and it's adjustment first.

 

Oil is in general an insulator but the type of base oil, how it was refined, the type of additive package, along with the type and concentration of contaminants will affect oil to conduct electricity.  This ability to conduct electricity in oil is measured in picosiemns/meter (ps/m).   Where clean SAE 10W-40 oil is >2000 ps/m and insulating fluids are rated at 12 ps/m. 

[int3man]

O.K.  Well let's put a Fork in it.   I should have titled it L.E.D. Back up lights on all the time.  I replaced the Back up light switch with a new one from O-Riely's.  The L.E.D.'s remained lit.  If I removed a L.E.D. Bulb and replaced it with an 3157 the lights all went out and work when the truck is in reverse.

 

So the problem is only present if I run L.E.D. Bulbs in the back up lights.  If I Run One L.E.D. and one 3157  it works O.K. Fine.

 

Sorry for any confusion.

Michael

When I get the truck back from the shop I will verify that the lights only light in Reverse. 

Edited April 1, 2019 by int3man

[Haggar]

Just a thought, but could the trailer connection have a small voltage leak in it?  (there is constant power there (from Fuse 8 pdc, along with the reverse lights.)

 

You may want to have someone look at the reverse lights (with the LED in)  while you have the park/neutral switch disconnected.  I am betting you have been doing the work by yourself so you would not have noticed them "still on" when disconnected.  So many people do weird wiring repairs and such at the trailer connectors....

 

GL  HTH

 

Hag

[int3man]

3 hours ago, Haggar said:

Just a thought, but could the trailer connection have a small voltage leak in it?  (there is constant power there (from Fuse 8 pdc, along with the reverse lights.)

 

You may want to have someone look at the reverse lights (with the LED in)  while you have the park/neutral switch disconnected.  I am betting you have been doing the work by yourself so you would not have noticed them "still on" when disconnected.  So many people do weird wiring repairs and such at the trailer connectors....

 

GL  HTH

 

Hag

Thanks for that!  A another source of Power.  And this just happened after I pulled the 7 way and towed a trailer.  HUMM

 

Thanks again 

Michael