Lionel 6-18953 Alco PA Horn won't shut off

Do you have other locomotives, ones that do not do this?

Mike

Yeah I have a K-Line signal sounds hudson that works fine. I also double checked an older postwar locomotive whistle tender and verified it works fine using the whistle button on the controller.

To get your manual follow this process:

1.) Type 6-18953 into the 'Search' box on the home page at lionelsupport.com.  Do NOT click on 'Go'.  Instead click on "New York Central TMMC Alco PA-1 Diesel A-unit #2000 - 6-18953":

2.) When the details page loads scroll way down to "Support Documents and Videos", then click on 'View':

Your manual will now download and appear in your browser.

Mike

Thanks for the info! Interestingly enough the manual shows a separate sound activation button to operate the sounds with this engine. I've haven't encountered one like that before, was always able to run them from the controller directly (using an MTH Z-1000). I wonder if it not having that could cause this behavior.

@TrainMan777 posted:

Thanks for the info! Interestingly enough the manual shows a separate sound activation button to operate the sounds with this engine. I've haven't encountered one like that before, was always able to run them from the controller directly (using an MTH Z-1000). I wonder if it not having that could cause this behavior.

Probably not.  The button is included with the engine so that the engine's bell can be activated if you're powering with an old-fashioned transformer that only has a horn button.

Your Z-1000 has both.

Back to the problem.  Since you have other engines that function normally on this track, then it's probably a problem inside the engine that's causing this, either a failure on the SignalSounds board:

Or on the LCRU:

These are in the parts list we called up on lionelsupport.com when we went looking for the manual.

Which one is it?  Three wires are the key to determining:

The voltage on two of them is supposed to change, one in response to a 'Horn' button push, one in response to a 'Bell' button push.  (The last one remains fixed regardless of which is button is pushed, or no button at all.)  If the LCRU is bad only one of these will change.  The other will be stuck, hence the stuck horn.

However, before taking or sending your engine to a service center, or replacing either of these boards yourself, there's one more thing to try.  Unplug them board, then plug them back in.  Doing so cleans the contacts.  This may restore proper operation without needing to swap in new parts.

Mike

Another thing to check for if the horn is sounding continuously, it is getting DC voltage. Does it sound in neutral? If not look for a wire touching from the solder terminal to the side of one of the motors.

I'd try it on another pure sine wave transformer, maybe it's a marginal flaw in the transformer.

Thanks for all the input guys! The sound appears as soon as powered is applied in neutral and remains in forward and reverse. I pulled the top off and re seated the connectors between the LCRU and Signal Sounds Board. Unfortunately the horn sound still persisted. I attempted to clean the contacts with alcohol but no dice still. The engine still runs okay without the board plugged in. I will have a look to see if there are any loose wires. I think my other transformer is buried but will double check. If my understanding is correct one of the three wires is power for the signal sounds board, the other two are for the horn and bell which will go high if the button is pressed. If I see two high voltages then coming out of the LCRU board without a button pressed then it likely indicates something wrong with the signal coming in or the board itself? Should the bell still sound in parallel with the horn when pressed or does signal sounds only support one at a time? The bell button doesn't seem to trigger the sound either.