Additional starter relay seizing the alternator

[Cat-a-tonic]

Like many others I had intermittant starting problems with a Yanmar 2GM20. Starter solenoid clicking but not starting. Many forumites recommend adding a relay into the ignition circuit to avoid voltage drop in the long ignition switch circuit. New relay now added and the starter motor now fires every time on the starter button HOWEVER the alternator now won't spin and makes an agressive chatter noises with or without the drive belt when the starter motor is activated. It's as if the alternator is fighting itself. My new circuit is simple, the old positive feed (from the B terminal on the start solenoid) to the ignition switch/start button is retained, the return goes to the new relay (85 pin) then to earth (86 pin). A new positive cable (from the B terminal on the start solenoid) goes to relay (30 pin) and out (87 pin) to the S terminal on the starter solenoid. That all works as hoped but somethings upsets the alternator. Re-configuring back to the original wiring and the alternator is happy again. What has the poor boy done wrong?

[JoeRobertJr]

Hi, Cat-a-tonic,
I tried sketching your verbal description, but could not follow. Any chance you could sketch your Before and After connections and post them?

[Kello]

Hahaha! ... sorry, couldn't resist. :-p Some years ago I was living in FL and for starting my Yanmar did the same thing - click but no joy. Went to Mastery and they sold me something like $120 in booster solenoid parts and other BS, and after two days of frustrating install, the starter solenoid wouldn't even click, so I went back to Mastry to return the parts and bitch. The guy I bitched at revealed that the problem was the skinny brittle wires used in the harness and the wires between the solenoid and key switch needed to be renewed (about a $2.00 and 2 hour project) but he didn't tell me that before because "nobody ever does that".


In the process of rewiring the solenoid / key switch I ditched the entire harness and rewired the entire panel with REAL wire and terminals, you'll need some electrical aptitude and time to figure out your harness and panel diagrams, but the rewards are worth it.


As for pins and alternator problems ... IMO, learn enough to rewire your engine/panel with real wire and buss blocks, ditch any booster solenoids, and go from there.

[leecea]

I don't really understand what's happening so this is a random guess...but does your alternator have a 3rd wire that requires a positive voltage when the engine is running and zero voltage when it is off? If so, can you check if that wire is seeing the same signal in the two different wiring configurations?

[RaymondR]

Being suspicious of the number of connectors between the cockpit instrument panel and the starter motor (which has a relay fitted) I wired in a push button, situated on the side of the engine box, in parallel with the Yanmar system. Have not had to use it yet but I know from previous experience I'm going to have a failure somewhere in all that wire and connections.

[OldGreyB]

"My new circuit is simple, the old positive feed (from the B terminal on the start solenoid) to the ignition switch/start button is retained, the return goes to the new relay (85 pin) then to earth (86 pin)"

Without seeing your modified wiring diagram or being there in person to fault find, your above description seems to indicate you are somehow potentially grounding the Alternator via the new relay coil circuit, causing it to chatter and be very unhappy.

See below as an example of how the wiring can be done to achieve your aim. Your engine wiring may be different.

[capalfie]

Originally Posted by Kello

Hahaha! ... sorry, couldn't resist. :-p Some years ago I was living in FL and for starting my Yanmar did the same thing - click but no joy. Went to Mastery and they sold me something like $120 in booster solenoid parts and other BS, and after two days of frustrating install, the starter solenoid wouldn't even click, so I went back to Mastry to return the parts and bitch. The guy I bitched at revealed that the problem was the skinny brittle wires used in the harness and the wires between the solenoid and key switch needed to be renewed (about a $2.00 and 2 hour project) but he didn't tell me that before because "nobody ever does that".


In the process of rewiring the solenoid / key switch I ditched the entire harness and rewired the entire panel with REAL wire and terminals, you'll need some electrical aptitude and time to figure out your harness and panel diagrams, but the rewards are worth it.


As for pins and alternator problems ... IMO, learn enough to rewire your engine/panel with real wire and buss blocks, ditch any booster solenoids, and go from there.

Well said! Totally agreed with that... Was there too...weak wirings, dirty contacts, all kind of small things to improve down there....the only good in good shape was...the usual suspect! It was always healthy...

Solenoid is being grateful since then and never failed again...
Cap Alfie

[skipperpete]

Originally Posted by Cat-a-tonic

Like many others I had intermittant starting problems with a Yanmar 2GM20. Starter solenoid clicking but not starting. Many forumites recommend adding a relay into the ignition circuit to avoid voltage drop in the long ignition switch circuit. New relay now added and the starter motor now fires every time on the starter button HOWEVER the alternator now won't spin and makes an agressive chatter noises with or without the drive belt when the starter motor is activated. It's as if the alternator is fighting itself. My new circuit is simple, the old positive feed (from the B terminal on the start solenoid) to the ignition switch/start button is retained, the return goes to the new relay (85 pin) then to earth (86 pin). A new positive cable (from the B terminal on the start solenoid) goes to relay (30 pin) and out (87 pin) to the S terminal on the starter solenoid. That all works as hoped but somethings upsets the alternator. Re-configuring back to the original wiring and the alternator is happy again. What has the poor boy done wrong?

Any chance the B+ to the alternator got left off or damaged when you hooked up the new supply cable to #30 on the relay from the solenoid B+ ?

[Cat-a-tonic]

Turned out to be a careless rookie mistake. I connected the relay earth wire to a live terminal on the starter motor that looked like a braided, unsheathed earth cable. Now connected to a proper earth and all is well. Sorry to tax your collective brains but thanks for all you responses.

[Cat-a-tonic]

Here's a rough simplified wiring sketch of my starter relay circuit as intended and implemented ( ignoring the rookie mistake stage).