Some electrical equipment on WITHOUT the master switch ON?

cessnadriver · #1 12-20-17, 08:01 AM

Hello everyone. Back again with more questions. While checking ignition leads with a lead tester, I removed the protective boot off of the, Battery side of the MASTER solenoid as a power source for the tester. WITHOUT the master switch on my turn coordinator started spinning up, my coordinator make noise when it first starts. I disconnected the battery positive lead from the master solenoid, to stop the turn coordinator/gear light, and replaced that solenoid thinking I had arched the connector plate inside. With a used solenoid from my other (parts) skymaster. It did the same thing-turn coordinator and gear down light came with the positive lead connected. My solenoid PN: S1578-1, having four (4) large connections posts, two upper and two on the bottom, and one small connection post, this type was ONLY used thru SN: 0525. On SN: 0526 the solenoid was replaced, by Cessna to a more standard solenoid, having two large posts and one small one, like the starter type solenoid.
Has anyone seen this type problem before? I did disconnect the two connections on the bottom two post from the PN: S1578-1, one wire is a jumper to the positive side post and the other goes to the "Generator" fuse. When I placed the generator wire on the opposite side of the positive post of the solenoid the turn coordinator and gear light does not come on until I throw the on the master switch on-BASICALLY solving the original problem BUT I'm NOT sure if the "Stand-by'-Run" switch will be affected?? Thanks for reading!
BILLS

JAG · #2 12-20-17, 09:01 AM

Bill,

I will have to look at the wiring diagrams tonight and respond. What is your S/N? I have not heard this before, but to be honest, I always connect right up to the battery. Basically, that is what you did, but for some reason it is activating the solenoid. Do you have a picture of your solenoid in the aircraft so we can see how it is hooked up?

Jeff

cessnadriver · #3 12-20-17, 08:30 PM

JAG. Thanks for the reply. My 1965 C337 is SN: 0200. I can get a picture of the solenoid BUT I've already removed the wires from the bottom posts? If you check the BATTERY CIRCUIT and/or Charging system schematics for SNs 001- 0525 they're the same. Cessna changed the part number and type of the solenoid, ie, from S1578 ( SNs 0235-0525 I think) to a newer PN is S-1580-1 which has been superseded several times since (But they are basically the same type). My worries are that moving the "generator" wire to a fuse from the Positive side of the solenoid to the load side may affect the RUN/STAND-BY switch? LET ME KNOW IF YOU STILL WANT THE PICTURE??
BILLS

JAG · #4 12-21-17, 10:28 AM

Hi Bill,

Since you already disconnected the wires - no need for the picture. I will go to the hangar tomorrow and take a picture of mine - so that we can compare. I will look at wiring diagram tonight. Likely back to you by tomorrow afternoon.
Jeff

cessnadriver · #5 12-22-17, 05:12 PM

JAG-Many thanks for the assistance! I look forward to hearing from you again. ALSO I see you're in Texas-where? I went to High school in Ft, Worth, TX, many decades ago!
BILLS

JAG · #6 12-23-17, 10:47 AM

Bill,

Here is a snap shot of your wiring diagram. Is this how it was wired before - or does this reflect how you have moved the generator wire now to the other side? The four posts on the older solenoid, was simply a way to get the standby power to the system when the master was off - solenoid relaxed.

This is a very strange problem - then again, electrical issues are always a challenge. Are you able to check to make sure the diode on the positive side of the solenoid is working?

Jeff