REVERSE LIGHT PROBLEM SOLVED - Thank you to everyone who helped out!

Nick, did you do a full factory reset,to restore all features

Alex

I looked up the manual and this engine has a Command reverse unit circuit board

I might be totally wrong but it's worth a try, to restore all features.

as norma

I performed the reset with the Legacy system, which is much easier. No change though.

Check if you have AC power to the plug, if so in probably a bad AD20 board.

Bill

If you reset by simply pressing the reset button that is not a "hard reset". For a hard reset you'll want to follow Alex's steps above.

It may not resolve the issue, but its worth a shot.

Rick, if you're talking about just pressing 0, no that's not what I did. I put it through the factory reset procedure for the Legacy remote, which simply consists of going to the engine info page, aux, and enter the code.

Bill, is the AD20 board available from Lionel or is that a small component?

Nick,  

691-PCB1-039 AD20A Check for AC voltage at the light first.

Bill

Nick,

Here's the part number and a picture of the board Bills talking about, which Bill can get for you .

Another thing that it may be worth checking before you start ordering parts, is the wiring harness to the light board. Check that it is firmly plugged in at both ends, and that all of the connections are good. 

Bill, what are your thoughts on a bad R2LC if it is not the AD20A?  This would be after powering the bulb to make sure it is good and a good point made by Nicole.   Before I start swaping out parts on anything Lionel, I pull and reseat boards and do the same with harness plugs. 

Nick, can you fire your rear coupler?  Just want to confirm your IR tether is working.

I thought that my backup light had an issue on my scale F7 ABA, each unit with its own Legacy module.  When I made a train from the motorized A and dummy B units I would not see the backup light turn on when I reversed the direction.  Appeared that the dummy B unit had a motion switch and required the train to move before the light actually turned on.  

Could your tender be the same way?

If it's just a light and everything else works, it might be as simple as replacing the triac on the receiver.  I'm assuming it's not the bulb.

If you swap tenders it will tell you if the problem is in the tender or engine. Then go from there.

Pete

I would think if the IR link is working to operate the couplers and the RailSounds, it would almost have to be in the tender.  Am I missing something?

I'm still waiting on the AD20A board to arrive, but last I checked it was definitely not the bulb since I replaced the PCB and it was still out, and the separate sale PT tender's light worked fine when I hooked it up to the Niagara so that tells me it's not a triac on on the R2LC. I did forget to check if the rear coupler worked and I'm currently away in NY until Sunday.

The old IR board can probably be fixed, my guess is it's the triac on that board that has died if the wiring and bulb are good.  If the audio control like whistle, bell, chuff, etc were working, the IR link would seem to be good.

John is correct.  I keep going back to what Nicole suggested.  I see more connections bad than components.

That's why I emphasized check for ac power at the plug.

Bill

Bad connections would certainly be the top suspect, and also the cheapest to fix.  It is odd the board would fail without some outside influence.

Are the marker light LED's not working also?

Marker lights light up fine, forgot to mention that. I'm almost tempted to believe I've possibly gotten two fluke main bulbs from Lionel in a row now.

Just for the 'fun' of it, try reprogramming with both engine and tender on the track with 740, instead of just 74. If you have a old cab one, try it with that.

I would apply 6V to the back up board pins for the bulb while removed from tender and see if they light.  If not the bulb is bad.  If it does check for voltage as stated and continuity of the wires to that plug.  G 

I always check bulbs and LED's by testing with 3 volts DC  (2 AA batteries & test leads) and then work up to 5 volts, then 9, then 12. BUT ALWAYS with the bulbs removed from their sockets and attached directly to the test leads. That way i'm sure a bulb is good or not.

jackson

even the title says "and bulb is not the problem".

did some thing change and I missed it. 

just asking.

The reason I go through the component swaps is because I have no testing equipment and have no idea how to use it even if I did. Electrical was simply never my thing.

Anyway, this would be the first time just swapping a component hasn't worked for me. It's basically beyond my ability to repair at this point and I'll be taking it to a friend that runs a computer repair shop.

Getting back to the Niagara.  The rear tender light works off the AD20A IR receiver in the tender.  The ground comes from pins 9 and 10 and the hot comes from pins 1 and 2.  On later Legacy locomotives with modular boards, the backup light has a constant hot and the light is turned on and off  by ground from pin 9 on the Railsounds audio board. 

Looking at the circuit board, the 'bulb' is actually an LED. And then after looking at the board in more detail, it appears to be powered through the right hand side and the centre pins of the connector.

I tried to follow the wiring on the harness to see where these leads went, but got lost along the way. Perhaps somebody else can unravel the connections? The white plug with the blue, grey & red/brown leads seems to be the best bet for the source of these leads though.

There do appear to be several places where a faulty connection could prevent operation though. This is quite a busy little harness.

The tender marker lights are LED's.  The backup light is a 14 volt lamp.  Without having it in front of me, the three wires should go as follows.  One wire for ground to be shared with both the LED markers and the 14 volt pin bulb.  This should come from pins 9 and 10 on the AD20A.    One wire will go to the LED hot connected to pins 1 and 2 on the AD20A.  This is track voltage (18V) and before the power finds the LED's the line has a 1K 1/4 watt resistor  in line to prevent the LED's  from blowing out.  The hot for the backup bulb will be connected to pins 1 and 2 on the AD20A.  This way the LED's will always be on with track power and when you tell the locomotice to backup, the AD20A will turn on the rear light.

Thanks for the explanation Marty. That is certainly an odd looking bulb though. The more that I looked at the photograph of it, the more it looked like an LED. Sorry for any confusion caused.

If the grounds are tied together and attached to pins 9 & 10 and hot for the LED and rear lamp are attached to pins 1 & 2, then the markers would turn on when the rear light was on. Having the LED hot and rear light hot tied to pins 1 & 2 and the LED grounded to chassis ground  the LED will stay illuminated. Grounding the rear light to pins 9 & 10 will allow the AD20 to turn rear light on  and off.

Bill

Bill is correct.  Sorry about that, the LED would be chassis ground.  A lot easier with it in front of us with the meter.  Not a bad system.

That's the truth!! A $10 volt/ohm meter and reading the instructions that come with it is less than the shipping charges every time another component is ordered. A very useful tool!!

Forgot to mention I did try this. Would not ever recommend it again, the tender emitted some rather frightening noises. Went back to normal after going back to 74.

Whoa now, do I spy two grey wires going to that 3-pin plug on the right? Mine is missing the middle grey wire entirely. There is absolutely no trace of it anywhere so I figured it was supposed to be like that. Does anyone know which supplement on the Lionel service page would have a wiring diagram of this tender? That would pretty definitively solve this mystery. Must have been a fluke that slipped through QC.

That settles it then. Will add the harness to the parts order I will be placing soon for another project.

Wonder how that managed to slip through QC...