Lionel 229 diesel switcher horn relay

Here is the wiring diagram for the loco.

To test the relay, take a good 'C' or 'D' cell and hook it across the coil wires with some jumper leads. The coil should pull in.

After you repair the wiring, put the loco on a track with a battery installed. With the power off, connect another battery to the center and one outside rail. The horn relay should pull in and the horn should blow. Now power up the loco pulling a few cars. Pull the whistle handle on the KW, and the horn should blow. If it does not, the whistle rectifier may need to be replaced inside the KW.

Larry

Can you blow the whistle on a different train with that KW?

The horn relay pulled in on the first test, so now I know it works. But it failed the second test on the track with the two batteries. So I'm assuming now that I screwed up the re-wiring. I downloaded your much better diagram, and will double check the connections.

Larry, checked the diagram you sent me, and everything looks correct. However, I have two other diagrams, and each one seems to vary a little. What confuses me is the hookups to the E unit. Mine has three terminals, yet on these diagrams they show four (?)  I'm a retired toolmaker, so the mechanics on these things are a breeze. Electronics, not so much.

A few things to check:

Is the battery bracket isolated (insulated) from the loco frame? It must be.

On the relay, are the two wires from the relay coil soldered to the correct positions at the front of the relay?

Check your wiring to make sure that there is no crossover between the circuit that operates the motor and the circuit for the horn. The only part of the horn, battery bracket and relay circuit that interacts with the loco is where the horn is grounded to the loco frame.

Well guess what? The wiring was correct, but there was a loose connection on the positive side. That corrected, the horn works fine. And the KW whistle button does activate it. Thanks to you electronics guys, you've saved my butt yet again.