Created a Electrical Problem

[edain08]

Did something stupid and could use a little help with pinpointing where I need to look to fix this,
1999 DIscovery 36T

Was troubleshooting some dim /burned out bulbs and put a single pin bulb into a 2 pin bulb socket - taking out the ground I suspect.
 

Symptoms:

with lights off - Left side turn signals work normally

                            Right side turn signal - all lights flash including running lights

 

With lights on - Left side works normally

                             Right side nothing flashes lights are just on

I have cleaned up/replaced grounds that had dicey connections and while all the lights are now brighter I still have the issue and I am running out of ideas as
to where I should be looking for the failed ground wire.

I would appreciate any ideas you all might have on where I should look/what I should attempt next.

[dickandlois]

edain08, Welcome to the FMCA Forum!

Symptoms:

with lights off - Left side turn signals work normally

                            Right side turn signal - all lights flash including running lights  Left , right ,front and Back?

With lights on - Left side works normally

                             Right side nothing flashes lights are just on.

The closest point to all the lights involved is the Turn Signal switch and the flasher units. Might just try replacing flasher units turn and 4 way.

Do you have the chassis electrical drawings for your coach? The 1999 Discovery is built on a Frieghliner Chassis if I remember correctly. 

Where you working on the turn signal bulbs with the flasher or one side of the turn signals operating?

Rich.

[richard5933]

Sounds like you created a short between the turn signal circuit and the light circuit. I'm guessing that the ground is the housing of the lamp socket and that the two contacts are for the signal and light circuits.

[sstgermain]

Do you have a signal light combiner that goes to the trailer plug wiring. You could have shorted one of the isolators in there.

[kaypsmith]

14 minutes ago, sstgermain said:

Do you have a signal light combiner that goes to the trailer plug wiring. You could have shorted one of the isolators in there.

Good point, and this would my first suspect.

[desertdeals69]

Call Frreightliner and they will send you a wiring diagram. I have a 98 Discovery on a Freightliner and they sent me a wiring diagram.

[edain08]

Ok I will try and reply to all

when right turn signal is activated with the headlights off - All the lights front, back, marker and clearance all blink

Can you tell me what the combiner looks like and how I would check/replace an isolator?

 

[sstgermain]

The combiner is a little box usually under the coach by the trailer wiring harness that has wires going in and ones going out. It is usually 2 or 3 inches long by maybe an inch wide. I have also seen a bad bulb cause that. Also look in the socket to make sure there is no short  Across the pins inside the socket.

The combiner combines the signal and parking lights on the rv side and combines the signals on the trailer harness side.

[kaypsmith]

The isolater is a diode inside the combiner. The combiner is a sealed unit, ususally black rubber looking, and as described above several wires in and several out. The primary purpose is to combine the turn signal on the coach with the appropriate brake light on the trailer, if your trailer harness plug has more than four wires, there will not be one on your coach.

[edain08]

Here are the results of my troubleshooting.  The final answer did not make any sense but here is what I did.

I started by removing the right rear taillight and examining the bulbs – no crossed filaments there.  Then I turned on the right turn signal and started removing bulbs.

I noticed that the flashers were acting strange so I replaced both flashers just in case they were part of all this but no luck there the lights just flashed better.

  After removing all the bulbs on the right side I still had the issue so I started replacing the bulbs.  When I got to a 194-marker light I failed to seat the bulb properly and it did not light up – not paying any attention I went to get the next bulb and noticed the problem had gone away.

I removed the 194 bulb and the problem came back – I put the bulb all the way  in and nothing changed. I replaced the bulb with a new one and the problem continued.  This perplexed me as this was not the bulb that I had replaced with the wrong bulb type.  I ran a new ground for the socket and that did not fix anything. 

I cut both leads and removed the socket and nothing changed so I replaced the 194 socket thinking it might be bad and as soon as I put the bulb in the new socket the problem vanished.

That was the fix.

[wolfe10]

Thanks for the update.

And congratulations on the diagnosis and fix.

[manholt]

Yep, very informative reading from all.  Great that the problem got fixed.

[jleamont]

1 hour ago, manholt said:

Yep, very informative reading from all.  Great that the problem got fixed.

your problem go away or do I need to pack extra tools in 3 weeks 

[dickandlois]

edain08 , Glad you got it working ! Could you post the location of the socket you replaced? The Rear Right or Right side marker? 

To me it sounds like the ground circuit for the flasher found a good ground when the socket was replaced, but it still needed a new bulb. Removing the bulb should cause the issue to return. The way the circuit reacted would have perplexed me also! IF It was a Rear light bulb socket, there is a harness connection at the passenger rear corner area, that is exposed to the elements. That connector does have a ground wire / circuit for all the rear lights except the trailer / Tow vehicle. 

Should the problem pop up again - find the mentioned connector and clean it with CRC, check the wiring and reconnect it. Did that resolve the original issue again?   

Here is the logic behind my thoughts - If like I mentioned above if the issue happens when the bulb is removed from the socket that solved the issue then you still have a week or open ground. 

Rich. 

[edain08]

Well I think I spoke too soon.  Problem came back this morning and would not go away.

 

Its the front turn signal lamp and the issue has got to be there somewhere.  I am guessing the 194 bulb just tripped me to the problem.  I am going to try replacing that socket on a hunch.  I could not find any bad grounds anywhere.  I would run a new ground to the flasher but I am concerned that it might cause new issues.

Any thoughts or ideas would be appreciated

[edain08]

Any chance this is the combiner?

[jleamont]

YUP, that sure looks like it! First thing I would do is remove the zip tie and electrical tape, look at the connections for corrosion. Also don't rule out the pinched wire under all of it 

[jleamont]

Just a thought, this all didn't begin to happen with an LED light change over by chance? Any LED's on the circuit?

[dickandlois]

8 minutes ago, jleamont said:

YUP, that sure looks like it! First thing I would do is remove the zip tie and electrical tape, look at the connections for corrosion. Also don't rule out the pinched wire under all of it 

The box size looks right as do the wire colors - they match the colors for turn signal and marker lights.

Rich

[edain08]

Not when it happened.  Just put in the wrong bulb type - Just for my info what is different about the LED replacement - I was going to do that later before all this happened

[jleamont]

When I swapped mine to LED the turn signals would'nt blink if the parking lights were on. Some locations on the Motorhome will switch the polarity of the power to the bulbs to make them alternate off of the other lights on the circuit. The LED lights will not function when this occurs, so you have you block the current that is back feeding. I had to install a bridge rectifier in the supply lines. Output wires (marked + and -) with polarity to match the LED bulb. Then connect the supply lines to the other two inputs. It doesn't matter which one connects to which.

I am and was lost, perhaps Kay could chime in, he helped me with it.

Rectifier parts;

https://www.amazon.com/dp/B071X9GMBR/ref=cm_sw_r_cp_api_X.uPzbR8F8998

[edain08]

Replaced the socket - no luck and am now replacing the combiner

[dickandlois]

Joe, I just use plane old diodes, that meet the current and reverse emf expected. The band goes to the lamp, relay or diode one wants to isolate.

Rich.

Most Diode / LED lights are polarity sensitive. Some of the more expensive ones have a circuit built into them that allow you to just plug them in and the circuit reacts to the polarity of the wiring. 

[edain08]

ok swapped out the combiner as well - still have the issue

I have checked every bulb on the right side and removed each one in turn and still had the problem except for the time the 194 socket was replaced which came back the next day.

I am flat out of ideas??  Any body got some?

[jleamont]

Edain, so you put a single pole bulb into a double pole outlet? What was the bulb number 1156/1157 style or 3156/3157? I'm trying to picture if you shorted to GND or other light circuit. 

Rich, was Freightliner Module happy in 1999 or did they jump in with that stuff later on? 

Does it do it with Hazards on also? 

If you are sure the grounds are clean I wonder if it back fed into the turn signal switch and damaged it. Most often everything passes through that switch, some have a small circuit board built in and diodes. I'm not familiar with that switch design in 99 on a Freightliner chassis.