802 relay assist

[Jeepadict]

Preface: I was drafting this as a PM to @kloppk when I realized the knowledge shared/gained would be better served as a thread in case someone else could also benefit from the knowledge. Cheers!

I find myself once again wrenching on yet another 802. This time my troubleshooting brain thinks there may be a common fault in a relay as both the oil pressure gauge and hour meter are both inop.

I've scoured the TM and have the testing process for both components printed and ready, but in studying the wiring diagram it seems they share a common relay. The TM troubleshooting is very obvious of replacing components assuming there is component failure and gives nothing to troubleshoot if the component is good yet inop. This is where I come upon my shortfall that I'm hoping you may know what I can't find in the TM: which relay is what?? I can see no labels on the machine...they all appear to be the same part...the parts and MX manuals make no differential between them that I can find. It seems someone else may or may not have gone down this path before me as 3 of the relay retaining clips for the 3 furthest right relays were found laying removed in the pan next to the relays.

I'm ready to go to town with my meter and start testing the components, but as I'm a retired airplane guy and not a ground equipment guy I want to have all my ducks in a row before I dig in. Do you have a secret source of wisdom that knows which relay is what?

Thanks in advance.

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[kloppk]

The wiring diagram in the -24 TM shows which relay is which.

 

[Light in the Dark]

I think the sheet metal case is tagged with these numbers too, but I think its on the back side of the relay base, so you won't see it unless the top is off.

 

[Jeepadict]

Thank you to both of you!

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[Light in the Dark]

Not the best photo by ANY measure... but taken quick off a parts machine here to confirm what I thought I remembered.

 

[Ray70]

So are you saying the Temp and fuel gages work and only oil and hour meter are dead??
Power and ground for all the gages comes from the same daisy chain so I would suspect ALL gages would be dead.
For the moment I would begin by checking 24V power at the gages ( and hour meter ) and if none, back trace using the schematic.

 

[Jeepadict]

Not the best photo by ANY measure... but taken quick off a parts machine here to confirm what I thought I remembered.

View attachment 885592

@Light in the Dark great minds think alike!

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[Jeepadict]

So are you saying the Temp and fuel gages work and only oil and hour meter are dead??
Power and ground for all the gages comes from the same daisy chain so I would suspect ALL gages would be dead.
For the moment I would begin by checking 24V power at the gages ( and hour meter ) and if none, back trace using the schematic.

Just now when playing musical relays I noticed the hour meter has decided to behave. That leaves only the oil pressure gauge remaining to troubleshoot, and I have the testing process for the gauge and sender from the TM ready to go for my next day off.

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[Guyfang]

Kurt has the relays.

 

[kloppk]

Kurt has the relays.

PM me if you need any. I have 6 or so new ones available.
Kurt

 

[Guyfang]

You hot tonight!

 

[91X15R]

Hello everyone, following this thread, the M3 (time meter) is contantly ticking, even when the DC fuse is out. Anyone experienced this problem on a 802A?

 

[kloppk]

Hello everyone, following this thread, the M3 (time meter) is contantly ticking, even when the DC fuse is out. Anyone experienced this problem on a 802A?

It would be best if you start your own thread about your M3 issue.
That way you'll get the right help and not have it get lost in this thread which is a different topic.

 

[91X15R]

It would be best if you start your own thread about your M3 issue.
That way you'll get the right help and not have it get lost in this thread which is a different topic.

Will do that, thank you. I searched for M3 and took me to this thread. Thats why I followed.