Engine Instrument Schematic - Please Critique

[Wotname]

Please critique this schematic of engine gauges (dash) schematic. A friend is renewing his engine dash panel (wiring, gauges, controls) and asked for a schematic.

This is the first draft, I will add wire gauge and circuit breaker values later once the basic design is confirmed.

The dash is located about 10' from the engine room. The battery bay is adjacent to the engine room. Engine is a Ford Lehman. The house battery system is not part of the rewire and is completely separate from the start/engine 12V system.

Comments please......

[Wotname]

Hmm.... 36 hours and no replies!

I wonder what the reason might be...

1. The drawing is perfect and no response needed.
2. The drawing is so wrong and there is so much to fix that a response is pointless.
3. No one looks at an hand drawn circuit anymore i.e. the person who still draws in pencil is an idiot so no response the best policy.
4. No one can read a schematic any more.

So without any other evidence, I'm going to take #1 as the most likely reason although perhaps #3 has some merit .

[mjscottinnc]

With the exception of a boat builder or really board electrical engineer, probably no one has ever taken the time to draw a complete schematic. Way more detail then most service manuals I’ve seen.

Nice job by the way.

[slug]

I only have an IPhone

As a result I can’t read the diagram

Dimmer on instrument lighting ?


Do remember to .... ignition ON .., engine room blower on

Also Alarm system ....engine exhaust temp

Exhaust temp is the most valuable alarm , seawater pump failure ...exhaust dry .. alarm instantly triggered , long before engine overheats

https://uflex.ultraflexgroup.com/en/catalogue/silenziatori-e-sistemi-di-scarico/09e09f-1/1553/exhaust-gas-temperature-alert-system.html

This sensor is the LAW on new builds

[omsray]

You have a Ground on the Volt Meter but where are the Grounds for the rest of the Gauges.

[Wotname]

Originally Posted by mjscottinnc

With the exception of a boat builder or really board electrical engineer, probably no one has ever taken the time to draw a complete schematic. Way more detail then most service manuals I’ve seen.

Nice job by the way.

Thanks, I do have some CV19 induced time ATM . Once the design is finalised, I will (probably) do some wiring diagrams (point to point wiring including terminals strips etc) and a BOM.

[Wotname]

Originally Posted by slug

I only have an IPhone

As a result I can’t read the diagram

Dimmer on instrument lighting ?


Do remember to .... ignition ON .., engine room blower on

Also Alarm system ....engine exhaust temp

Exhaust temp is the most valuable alarm , seawater pump failure ...exhaust dry .. alarm instantly triggered , long before engine overheats

https://uflex.ultraflexgroup.com/en/...rt-system.html

This sensor is the LAW on new builds

Good point about the exhaust temp alarm and I concur! I will talk my friend into getting one. He doesn't currently have a engine room blower and that might be a bridge too far for him.

Dimmer on instrument lighting - well the dash is mounted in the cockpit and it is a nice to have thing at night (plus cheap and easy). Perhaps a hangover from my aviation days - especially when designing Night Vision cockpit lighting .

[Wotname]

Originally Posted by omsray

You have a Ground on the Volt Meter but where are the Grounds for the rest of the Gauges.

You have to look closer (or perhaps I should use a bigger pencil)

Here, does this help

[omsray]

My recommendation is to draw in the Ground wires from Gauge to Gauge to make it Obvious, especially if you are doing this for someone else to do the wiring.

[jimbunyard]

Just saw your post, so I'll give it a go...

Looks kosher to me, but there are several things (that should probably be self-evident) that I don't understand.

Abreviations; AFD (under the master switch [or is that RED?]), NN.

Symbols; Arch topped with a 'T'.

An internal switching diagram of the starter/solenoid could be useful.

Better labeling of the alternator connections as well.

A wire color legend and labeling simplifies things.

It appears there is a warning lamp for low oil pressure but not for high temperature?

Would be easy enough to add high temp/low oil pressure shutdown (2 relays, 8 wires) if the added complexity isn't a problem.


Now you can critique my critique, cuz I'm usually pretty good at missing the obvious...

[Wotname]

Righty Oh...And thanks for your input.

Originally Posted by jimbunyard

Just saw your post, so I'll give it a go...

Looks kosher to me, but there are several things (that should probably be self-evident) that I don't understand.

Abreviations; AFD (under the master switch [or is that RED?]), NN.

Automatic Field Disconnect (which is mechanically ganged to the master switch contacts and operates just before the main contacts open). The dashed line between the main contacts and the AFD indicates all contacts are in the switch body.

Symbols; Arch topped with a 'T'.

Circuit breaker and the 'T' indicates it can be manually tripped.

An internal switching diagram of the starter/solenoid could be useful.

Better labeling of the alternator connections as well.

Both are fair comments

A wire color legend and labeling simplifies things.

Those aspects will be part of the wiring (or interconnect) diagram. I usually do a schematic first to make sure everything is electrically correct and follow up with a wiring diagram showing where each and every wire is terminated. A bill of materials (BOM) will list all the parts needed to complete the project.



It appears there is a warning lamp for low oil pressure but not for high temperature?

It is located between the charge lamp and the low oil pressure lamp and abbreviated as 'TEMP'.

Would be easy enough to add high temp/low oil pressure shutdown (2 relays, 8 wires) if the added complexity isn't a problem.

Good point and I will give it some consideration in conjunction with the owner of the boot.


Now you can critique my critique, cuz I'm usually pretty good at missing the obvious...

[Wotname]

Originally Posted by jimbunyard

..........
Would be easy enough to add high temp/low oil pressure shutdown (2 relays, 8 wires) if the added complexity isn't a problem.
..........

OK, have added an auto shutdown for exhaust over temp, coolant over temp and low oil pressure.

Haven't done an auto shutdown before but I think I have it right. Please advise if otherwise.

Simple schematic below using two relays and a disable switch (circuit protection etc not shown). R1 activates the STOP solenoid in the event of an alarm and R2 disables the circuit when starting. The auto shutdown disable switch deactivates the circuit should faults occur causing nuisance tripping.

[Nord Sal]

Glo plug switch?

Instrument lights? (I see dimmer)

Hour meter?

[Wotname]

Originally Posted by Nord Sal

Glo plug switch?

Instrument lights? (I see dimmer)

Hour meter?

Thanks for your input Nord Sal, it's appreciated.

Glo plugs not fitted to the engine.
Currently the dimmer drives the internal instrument lighting but an external panel light(s) might be fitted.
The hour meter is cleverly disguised as "Hobbs Hour" on the circuit .