GM 4905 Turn Signal Relay/flasher unit

[chessie4905]

Here

[chessie4905]

Here

[chessie4905]

The turn signal flasher is a module, not the usual tin can. GM most likely used a "robust" flasher to handle hundreds of hours of turn signal and 4 way flasher use. Many times, these coaches would sit at terminals or other locations with 4 ways on for an hour or more. They needed a unit that would hold up to this use.
If you want to change to an led flasher, some time with the wiring diagrams and a conventuonal socket will be needed
Btw, some of those pictures are sideways to get a good image

[richard5933]

The turn signal flasher is a module, not the usual tin can. GM most likely used a "robust" flasher to handle hundreds of hours of turn signal and 4 way flasher use. Many times, these coaches would sit at terminals or other locations with 4 ways on for an hour or more. They needed a unit that would hold up to this use.
If you want to change to an led flasher, some time with the wiring diagrams and a conventuonal socket will be needed
Btw, some of those pictures are sideways to get a good image

Do you know if there is a modern equivalent part for the flasher module? Or, are they still available should someone need one? The part number in my parts book (675551) doesn't appear to be a current part number from what I can see.

I do see heavy duty 24v two-wire flasher units out there, complete with heat sinks and all, but none with the same or similar numbers.

[chessie4905]

You could call Luke.

[richard5933]

Was talking to Luke about something else this morning, and I asked him about the flasher assembly. He has an updated version of the flasher available should anyone need. FYI

[pabusnut]

John, Thanks for the pictures-that is what I have. 

I am "Deep in the Heart of Texas" right now and the turn signals worked about 90% of the time on the trip here from Blytheville. I will be revamping the whole system when I get home, as it drives me nuts to have to fiddle with them to get them working while driving- and constantly check to make sure they are on. 

I already have my "Christmas list" ready - so Luke will be getting some more business near the end of the year.  That updated flasher unit may be on it.

[richard5933]

John, Thanks for the pictures-that is what I have. 

I am "Deep in the Heart of Texas" right now and the turn signals worked about 90% of the time on the trip here from Blytheville. I will be revamping the whole system when I get home, as it drives me nuts to have to fiddle with them to get them working while driving- and constantly check to make sure they are on. 

I already have my "Christmas list" ready - so Luke will be getting some more business near the end of the year.  That updated flasher unit may be on it.

What specifically are you fiddling with to make the turn signals work?

You can easily bench test the flasher unit to see if it's working properly. The wiring diagram in the book should show you how it's wired - if you don't have a wiring diagram let me know and I'll post one.

If they are intermittently working, then my guess is you have a lose wire/bad connection/bad ground in the system.

Knowing if the problem is on one side or on both sides will let you know which half of the system you're dealing with. It's a pretty simple setup once you work through the diagram a few times.

[chessie4905]

Very common to have wiring issues at tailgate lights and wiring. That area gets all the dirt salt and gets corrosion issues in the wiring. Eliminate all crimped butt connectors. Clean, solder, and double shrink wrap all the connections with second shrink a little longer than first one. Especially check all the ground connections to the lamps and where they are attached to the lamps.