28 series runs with wire disconnected.

bertsmobile1 said:

If you clean off the cover with steel wool or scotchbright pad, not abrasive paper the take several photos at different angles with a digital camera on a stand of some kind so it will be in sharp focus.
Now load the photos into your computer and play with the contrast
Generally the number will become very apparent.
If not then invert the colours ( make a negative in some photo apps )

Note this needs to be done with a real camera set to the highest resolution, not a phone or I pad thingy.

Click to expand...

Thanks for the advice. That was my thought. When that approach failed I even tried etching the cover and using a UV light. Still nothing, so I suspect a "bitsa" tractor mower with an engine scavenged from another application. Even possibly deliberate removal so as conceal a stolen engine, or am I being paranoid? (I got the tractor very second hand, but at a sensible price and readily made serviceable. Previous Owner alleged to have been a Cricket Club, so who knows who the maintainer was?)

Bogart said:

It is a 280H00 series engine.

Sorry in the delay.

Regards

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I am very much obliged. Now that I have the documentation and looking at the engine as a whole, mine appears to be a 21 series after all. Possibly a later replacement by Previous Owner.

Regarding non-start; I am down to spurious earth/ground on the engine kill wire or connected loom, or faulty PCB as the cause. I can remedy by removing the kill wire from the engine, but the clutch will not energise even with the engine running and seat switch depressed. Another hour or so with the multimeter eh!?

Replacement rocker covers come with no numbers.
Mowers owned by clubs get a hard life so very good chance someone levered it off with a screwdriver thus bending it beyond reuse.
Power for the PTO comes via the ignition switch engine off and via the alternator engine on , done through the ignition switch.
All mower are wired basically the same and briggs did a nice little booklet to help you through id you do not have the makers wiring schematic.
https://www.vanguardengines.com/content/dam/briggsandstratton/na/en_us/Files/FAQs/alternator_replacement.pdf

Sounds familar to mine as I had to remove the kill wire to get her to start. Used it for a while with it taped to the bonnet and if I wanted to stop just touched it to the body. Finally fitted a new switch in place of the keyswitch which was falling to bit as well. Now if I switch it to off it then grounds the kill wire and she stops. Had to hard wire the cutter clutch as that did not work easy enough job. I think mine has a duff pcb some bits work others not. The engine revs fuel gauge all ok but no interlocks work including seat same as yours. I am not willing to spend £150 plus on a new pcb as she is working even if it is to my design.

{quote}Sounds familar to mine as I had to remove the kill wire to get her to start. Used it for a while with it taped to the bonnet and if I wanted to stop just touched it to the body. Finally fitted a new switch in place of the keyswitch which was falling to bit as well. Now if I switch it to off it then grounds the kill wire and she stops. Had to hard wire the cutter clutch as that did not work easy enough job. I think mine has a duff pcb some bits work others not. The engine revs fuel gauge all ok but no interlocks work including seat same as yours. I am not willing to spend £150 plus on a new pcb as she is working even if it is to my design.
{/quote}

Strange that!

Now that I have cured the start problem I am left with a deck clutch that will not energise. Wiring and clutch diode check out OK; just no voltage to the clutch.

I did bite the bullet and get a new PCB; no change, but the same symptoms (so now I have a spare PCB).

Viz:

• When ignition is switched on the PCB self-checks and is OK. Battery state red, clutch/brake green when set, otherwise green goes out as it should.
• Engine starts and runs.
• Seat switch is ignored and the engine keeps running when I leave the seat.
• Clutch will not energise when seated normally and engine running.
• Battery warning light persists, even though battery volts are 12.38 at tickover and rising to around 12.78 when running faster. That is, normal.

I have found that the voltage to the seat switch to be only 8v, and the PCB sends nothing to the clutch. (Next stop = main loom change?)

I have a working theory that the PCB is seeing low volts (either bad supply volts or bad ground or short somewhere) and does not function properly. What I am missing is the cause.

Suggestions or alternative theories welcome.

That looks wrong.
Most safety switches are ground switches.
A bit hard with the new GGP mowers because they are going to solid state switching via chip on the PCB so one does not know what is connected to where but from the circuit diagrams I have seen they all ground circuits as a coloured wire connects to a common ground so you can not have 8V connecting to ground or you will end up with a short and the smoke will get out of the wire.
I can see why Bogart did some alternative wiring.
Without switching information anything I could all would just be speculation so I get to dip out now but I am looking over your shoulder.

Definitely looks like ALUCAN and I have the same problem, glad you bought the new pcb and not me. Like you my seat switch does nothing as regards stopping the machine though he switch is working fine. I came to the conclusion what the hell get it working to my design and who cares if things are not as manufactured. Just hard wire the cutter. I replaced the original switch and feed it directly from the battery via a fuse. Mine has only a few weeks left before I am going to trade it in for a Husqvarna.

bertsmobile1 said:

That looks wrong.
Most safety switches are ground switches.
A bit hard with the new GGP mowers because they are going to solid state switching via chip on the PCB so one does not know what is connected to where but from the circuit diagrams I have seen they all ground circuits as a coloured wire connects to a common ground so you can not have 8V connecting to ground or you will end up with a short and the smoke will get out of the wire.
I can see why Bogart did some alternative wiring.
Without switching information anything I could all would just be speculation so I get to dip out now but I am looking over your shoulder.

Click to expand...

Bingo! :thumbsup:

Thanks drawing my attention to the glaringly obvious - "Most safety switches are ground switches".

Therefore if there are volts showing either the second PCB is goosed, or there is a short-feed from elsewhere. Trace back to Fuse F3 and beyond should provide an answer. I will let you know how I get on.

Bogart said:

Definitely looks like ALUCAN and I have the same problem, glad you bought the new pcb and not me. Like you my seat switch does nothing as regards stopping the machine though he switch is working fine. I came to the conclusion what the hell get it working to my design and who cares if things are not as manufactured. Just hard wire the cutter. I replaced the original switch and feed it directly from the battery via a fuse. Mine has only a few weeks left before I am going to trade it in for a Husqvarna.

Click to expand...

Hmmmmm. Last ditch option for me. I prefer safety devices to work. If all else fails I can always put in my own relay-fed supply to the clutch. Not really complicated, but hopefully un-necessary if I can fix it. See previous post.

The only safety that I really believe is important is the seat switch.
Firstly it makes you apply the brake before you get off so it does not run away or even roll a bit when you step back on with the blades running ( because they was bypassed )
Secondly it protects others should something happen and you pass out or fall off.

THis is the basics of how mowers are wired, without the PCB
https://www.vanguardengines.com/content/dam/briggsandstratton/na/en_us/Files/FAQs/alternator_replacement.pdf