Why is a PS2 GP-38 trying to eat my TIU?

I think you need to consider taking it to a shop that knows how to test the boards and has the test equipment.

The manual https://mthtrains.com/sites/de...ction/20dl17182i.pdf

Knowing that PS2 is DCS signal polarity sensitive is important. PS3 engines are not DCS signal sensitive. I've never broken down exactly what happens other than the engine has problems responding when a DCS signal polarity is not correct, maybe there is chatter or interference with other engines and the TIU. Point being, the manual covers this and this Premier engine has a polarity switch. So it's possible that got changed or bumped. Again, one possible explanation why this engine cannot be found by a remote/app or added under DCS where other engines work fine?

#2

Thanks Vernon and John. I didn't know about that switch, as I only have (2) PS2 locomotives. When I powered up the track just now, (7) PS3 locomotives and the (1) sister PS2 all moved from "active" to "inactive" and I got the "No TUI/WIU Found" like I had been.  What still bugs me is why it ran for 6 months and then up-ended. I'm going to take it to the medics, as John suggested.

try running the engine in conventional ( no DCS or tiu hooked up)

More importantly to also do a shut down test to see if the battery is any good. A dead battery may cause this issue.

I believe the polarity switch is for 2 rail use only!

Joe is correct polarity only controls 2 rail.  In 3R the polarity switch does not matter.  I have not see a PS-2 engine kill dcs to the layout though I have seen PS-2 engines that can not see DCS.  Normally it is the Power Supply board, but I have several PS-2 5V like that and one 3V processor that won't read DCS.

Now, a PS-3 engine can work, but have reflective effects on other engines, killing the DCS signal.  So for all your PS-3 diesels, you need to make sure the wiring harness is routed properly over the laid down capacitors to prevent killing DCS signal.  You may have more than one problem here.  You will need to be methodical in isolating.  Right now, too many variables.  Do you have a remote?  I go TIU only and test engines signally to verify entire layout and each engine.  Once your satisfied TIU and layout are good along with individual engines, add one engine at a time and test, until you have a problem.  G

Thanks GGG and others!

Just a couple notes. I have 12 or 13 running PS3 engines and 1 PS2 engine that all work fine. I do not have a remote. I did disconnect a lot of track, and I've been down the one-engine-at -a-time routine, which is how I managed to isolate the single PS2 engine being the subject of this thread. Here's a play-by-play, dealing only with this one engine:

• track, TUI, WIU are un-powered
• Power TIU. WIU
• set subject on un-powered track
• power track
• open iPad APP
• Search new DCS engine (It was on my iPad until I deleted it)
• at this juncture, the arrow above the horn  blinks continually (see photo of iPad)
• the pink "TUI" light on the WIU blinks once per second. I does not stop.
• error messages on the APP abound. I've seen them all! They don't stop either
• NOTHING runs
• remove engine
• power down the entire room
• go away

I go away for 10 minutes and when I re-boot without that engine, everything is back to normal and running fine. This includes my several MU lash-ups. They all work fine.

The sequence in the bullets has been repeated now countless time with the same result. I have yet to look inside the engine, but failing to see anything obvious, I will have to bring to someone.

For what it's worth, the clock on the engine (back when it  did run) in fact, had low hours. The subject engine run conventionally with no issues. Also, to my knowledge, no other engine has ever made the pink TIU light blink  continually or the APP arrow blink.

Thanks again,

Bob

Response to GGG's post:

I should have been clearer with my post. I don't mean that a dead battery kills DCS signal. I meant a dead battery can cause the remote to get stuck trying to get a response from the engine when it doesn't respond correctly. Now that is just a guess from me!

The app is much faster but a dead battery can still cause grief. I'd have to have a fantastic memory to list all the things that happened over the years from this. Each version of DCS probably reacted differently each time.

Response to pink TIU light: I've never seen that!!

I could easily see a dead/weak/worn battery causing issues with the charging circuit and pulling a power supply rail on the board low. Stuff like that can cause all sorts of weirdness.

Update:

I just replaced the (blue) battery with a new BCR2 I had on the shelf. No change. Still dumps the TUI/WUI.

There was a small sticker the belly indicating the battery was new in January of 2021. Not old but I replaced it anyway.

Thanks to everyone who chimed in here.

Time for Plan B.....

@endless tracks posted:

Thanks GGG and others!

Just a couple notes. I have 12 or 13 running PS3 engines and 1 PS2 engine that all work fine. I do not have a remote. I did disconnect a lot of track, and I've been down the one-engine-at -a-time routine, which is how I managed to isolate the single PS2 engine being the subject of this thread. Here's a play-by-play, dealing only with this one engine:

The subject engine run conventionally with no issues. Also, to my knowledge, no other engine has ever made the pink TIU light blink  continually or the APP arrow blink.

Thanks again,

Bob

it's got me baffled. You did test it again, right?

It sounds like the engine has a short but now, it's over my head!

Joe,

Yes, tried to run it again this morning after I swapped the battery out. No-go. It still locks out the TUI and WUI. I had a new PS3 engine just idling and "Active" on my app.  As soon as I tried to "Add (THIS PS2)MTH Engine", the PS3 went "inactive" and just continued to idle.

It subject PS2 engine does run fine on conventional power.

Always something new with these gadgets, eh??

Given that situation and results, my next level of testing would be swapping the PS2 3V upper "power board" since that contains the power circuitry but also the DCS signal transformer with a known working one.

I'm not saying this is it or the board replacement is the magic fix, just saying, you tried to isolate it to this engine, you've done resets, you've changed the battery.

The power board is "agnostic" meaning it's not engine specific. The lower logic board of the PS2 3V stack is what is programmed specific to the engine.

Thanks Vernon. Given that tax day is closing in, I'll have to take this up another day. Since the power board is "agnostic" (good analogy), would a GP35 or a GP40 PS2 board fit that GP38?

@endless tracks posted:

Thanks Vernon. Given that tax day is closing in, I'll have to take this up another day. Since the power board is "agnostic" (good analogy), would a GP35 or a GP40 PS2 board fit that GP38?

Yes, exactly what I was implying- borrow a known working one from any PS2 3V set. Could be steam or diesel. This is why I have a bunch of PS2 3V starter set 2-8-0 engines and tenders open with no shell- ideal for testing and board swaps.

If it works then fine- your options are buy a new one from MTH- or someone that may know more about fixing that PCB at the component level.

I think the answer was- nobody has seen this symptom before exactly. It might be the board, it might be something else, just an unknown.

I would not do that.  If you do not have a power supply with current and voltage meters, and a basic ideal of what can go wrong you risk having a processor board that will eat your working power supply board.  Then you could have two engines bad.

I have never seen this symptom.  For the engine to take out the track it has to be heavy damage.  When that happens to the Power Supply board it usually means a bad processor too.  Take the board out of the engine and send to a tech who does board testing repair.  I can do this work, it you don't have your own tech.  G

@SIRT posted:

If it has a switch, it might be set to 2r?

That results in no power or anything.  Per GGG and my own experience last night in troubleshooting a similar PS2 3V engine with 2R/3R, the polarity switch is the 2 wires from the trucks for the left and right side wheels, the 2R/3R switch is then after that and connects either the 3rd rail pickup and/or outside wheels to the 7 pin input harness of the PS2 stack. Point being- it completely disconnects the 3rd rail pickup when in 2 rail so again, switched the engine would have no power- nothing at all on a 3R track.

This does run in conventional just not DCS

@endless tracks posted:

This particular locomotive had been running without a problem since I bought it last summer. Never an issue with it until now. It does run conventional as it should but trying to run command is off the map.

And, I agree, sending to a tech is the best bet for fixing without invoking more damage.