Daihatsu Skywing (with stupid owner) - Mains Damage To Car Electrical System | Technical matters | Back Room Forum

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Mon 30 Mar 2020 16:57

Daihatsu Skywing (with stupid owner) - Mains Damage To Car Electrical System - edlithgow

The Colourful Ethnic Starter Switch described here

https://www.honestjohn.co.uk/forum/post/index.htm?t=114209

stopped working, and for a while I've just been using a 2-core power cord with both wires on a single croc clip on one end, and a 2-prong moulded on plug on the other. Touch either prong to the starter terminal with the croc on the battery positive to turn the engine over

In retrospect, this was an accident waiting to happen, Someone with less over-confidence than a nuclear power station designer might have bent the two prongs together with pliers, but sadly I was not that someone.

So on Sunday I dead-shorted 120V AC mains through this lead when it was connected to the battery +ve. Thought I was plugging in a light.

No power now to the room, so awkward interview with landlord (who doesn't like car maintenance and would probably have something in the lease against it if he'd ever heard of it before) looms. Hopefully just a circuit breaker but I dunno yet.

I assume I'll have fried the diode pack on the alternator. Can't get parts for this car now but perhaps these (or a whole new alternator) are generic?

Fortunately this is an old car and AFAIK that (and a clock) is the only electronics on board,

Might the battery have survived? Whatever it was that tripped or fuzed by design or (worst case) melted by accident did so sharpish and the lead was only warmish to the touch.

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Sat 4 Apr 2020 10:36

Daihatsu Skywing (with stupid owner) - Mains Damage To Car Electrical System - Peter.N.

I've done things as stupid as that and I was an electronics engineer for 50 years!

I don't think the Skywing has much electronic equipment on board so it won't have done to much damage- I may be wrong but I hope not.

Was the lead connected to the starter and battery so the mains was applied to the small connection on the starter? If so and the mains tripped out immediately it should,nt have done to much damage.

What exactly is the car doing now, do you have instrument lights, does it do anything if you try to engage the starter?

I doubt it would have effected the alternator although can't guarantee it

Edited by Peter.N. on 04/04/2020 at 10:38

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Sat 4 Apr 2020 16:46

Daihatsu Skywing (with stupid owner) - Mains Damage To Car Electrical System - edlithgow

Thanks for your reply.

I had what seemed to be an ignition problem (poor-looking and erratic spark, difficulty starting and failure to run for very long) which I was looking at when I made this mistake.Not sure if the points were closed at the time. The starter lead connected mains AC directly to the battery positive, but it was also a short so tripped the breaker.

The original problem seems to have been the points, (See the other thread about that.)

I cleaned them up, put them back on and roughly set gap and timing this afternoon, Started and seemed to run OK, so the primary and secondary ignition circuits cant be badly damaged.

Dunno about charging yet, but that was already perhaps a bit iffy since the battery light would come on intermittantly. I'll have a look at charging tomorrow'.

If I get away with it that'll be a reason to run an old car,.

If I don't get away with it that'll be another one.

Edited by edlithgow on 04/04/2020 at 16:54

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Sat 4 Apr 2020 17:54

Daihatsu Skywing (with stupid owner) - Mains Damage To Car Electrical System - John F

Thanks for your reply.

I had what seemed to be an ignition problem (poor-looking and erratic spark, difficulty starting and failure to run for very long).......

Have you tried replacing the condenser? Many years ago doing this cured a similar problem with my TR7.

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Sun 5 Apr 2020 06:13

Daihatsu Skywing (with stupid owner) - Mains Damage To Car Electrical System - edlithgow

Thanks for your reply.

I had what seemed to be an ignition problem (poor-looking and erratic spark, difficulty starting and failure to run for very long).......

Have you tried replacing the condenser? Many years ago doing this cured a similar problem with my TR7.

See other thread. I did some half-baked testing with a multimeter which non-conclusively suggested it was OK.

Dkifficult to get automotive spares here but I can probably use eBay or just source a general-purpose capacitor here, though that might be a bit harder to fit.

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Sun 5 Apr 2020 11:03

Daihatsu Skywing (with stupid owner) - Mains Damage To Car Electrical System - edlithgow

Battery voltage 13..12V

Drops to 10.V8 while cranking. Recovers to 12.35V 2nd time recovers to 12.34V after a 5 sec cranj..

Engine running 14.30V at about 1200 rpm

2500 rpm, stays below 15V. After that idle speed is higher (1500) and voltage between 14.7/14.8

So, no obvious (to me) indication of a battery or charging system problem, except thatr the dash charging light (battery symbol) was lit some of the time.

Suggestions for further testing?

I might put a permanent voltmeter on the dash,

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Sun 5 Apr 2020 12:30

Daihatsu Skywing (with stupid owner) - Mains Damage To Car Electrical System - bathtub tom

The dash light could indicate there's a problem. Alternators are three-phase devices with full wave rectification, so the output is a series of humps. The way to see this is to put a CRT on the output.

I lost a phase due to a faulty diode pack once that showed up as a warning light reluctant to go out.

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Sun 5 Apr 2020 15:24

Daihatsu Skywing (with stupid owner) - Mains Damage To Car Electrical System - edlithgow

Thanks for your reply

Re ""The way to see this is to put a CRT on the output", Do you mean an oscillosope, or it has to be an actual CRT?.

Unsurprisingly I don't have either, I have seen mention of the possibility of using a smartphone audio input with foil inductive pickups on the ignition leads for looking at the ignition signal waveform.

I'd doubt such an indirect connection would work for the low voltage charger output, though and I wouldn't much fancy connecting it directly

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Sun 5 Apr 2020 20:12

Daihatsu Skywing (with stupid owner) - Mains Damage To Car Electrical System - bathtub tom

Yes, sorry, I meant a 'scope. Don't know why typed CRT.

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Mon 6 Apr 2020 10:04

Daihatsu Skywing (with stupid owner) - Mains Damage To Car Electrical System - Peter.N.

You must be old like me Tom.

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Sun 5 Apr 2020 21:56

Daihatsu Skywing (with stupid owner) - Mains Damage To Car Electrical System - Brit_in_Germany

Maybe someone will have a suggestion as to how to modify a TV cinch cable input so you can use a flat screen display as an oscilloscope.

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Tue 7 Apr 2020 01:49

Daihatsu Skywing (with stupid owner) - Mains Damage To Car Electrical System - edlithgow

Maybe someone will have a suggestion as to how to modify a TV cinch cable input so you can use a flat screen display as an oscilloscope.

I've seen Youtubery on doing that with old CRT TVs / monitors, but I chucked mine a few years ago. Too bulky to store on a "might come in handy" basis, even for me.

There's this

https://www.instructables.com/id/Digital-Oscilloscope-With-LCD-Screen/

but I havn't got time to read it right now.

Looks complicated/expensive

Edited by edlithgow on 07/04/2020 at 01:54

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Sat 18 Apr 2020 13:03

Daihatsu Skywing (with stupid owner) - Mains Damage To Car Electrical System - edlithgow

Took it in for inspection Friday. Drove fine, though the idle (already high due, I think, to a damaged idle adjustment valve/seat in the carb) rose to around 2000 rpm.

Vacuum guage mounted on the bonnet provided some in-car entertainment though keeping the vacuum high probably meant I got passed even more often than I usually do.

Quite a long queue for inspection and the car overheated, boiling the coolant. Fan not cutting in.

Limped it back home and at one point, while attempting to jumper the fan directly off the battery, got the wrong terminal, shorting to earth.

Relay seems OK, fan runs, BUT both solenoid contacts on the relay show 3V when they should be off. Wondering if this is an internal short due to damaged wiring loom.

Checked through fuses and replaced a blown 15A "engine"" fuse, and the mystery 3V went away.

Last time this happened (also in the queue for inspection) I think I jumpered the block sensor directly to the relay solenoid, but can't get that to work now. Spose I'd better check the temperature switch again.

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Sat 18 Apr 2020 13:55

Daihatsu Skywing (with stupid owner) - Mains Damage To Car Electrical System - Oli rag

I’ve had myself similar odd readings on various different machine I’ve been repairing. These strange voltage readings can be caused by carbon tracking inside the blown fuse, which will conduct enough to be read on a sensitive multi meter but won’t allow enough current flow to operate the equipment.

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Sun 19 Apr 2020 02:33

Daihatsu Skywing (with stupid owner) - Mains Damage To Car Electrical System - edlithgow

Mystery 3V is back, except its now a mystery 1.78V, which I suppose is progress of a sort.

"But there's something else. Something even worse which I must not think about."

(Sorry, I THINK I'm quoting Einstien in Serendipity there)

But seriously though.

A bullet connector terminal which was loose and I THINK was originally on the engine temperature switch. (There is also a loose spade connector which doesn;t seem to go anywhere. Surprising this thing is running at all) appears to be cycling between about 1.5V and about 10V, ignition on, engine off.

Doesn't look like just an intermittent/bad connection. Looks to be actually cycling.

Even with the internal loom melting I'm afraid of , I can't think of anything on this basic 1980's car that would do that, though I daresay there'll be lots of electrickery candidates on something newer.

Voltage regulator?

Anyway, I'm going to ignore that for now.

I think my next step will be to try and disconnect the relay solenoid circuit from the cars while keeping the fan power circuit connected, and then jumper the solenoid directly.

You can apparently buy adapters for this kind of thing, but of course not in Taiwan, and I wouldn't use it enough anyway..

https://www.youtube.com/watch?v=YElByNoAz90

Lisle Relay Test Jumper Kits # 56810 SOLD HERE: www.summitracing.com%2Fparts%2Flil-56810%3Fseid%3D...n" target="_blank">http://www.summitracing.com/parts/lil...

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Sun 19 Apr 2020 05:37

Daihatsu Skywing (with stupid owner) - Mains Damage To Car Electrical System - edlithgow

Runs fan when solenoid is jumpered directly to battery

I'm assuming I should be seeing around 12V on one of the solenoid terminals (dunno which one, or if polarity matters)

One (RHS) connector shows earth continuity, and I assume that will be the one that makes the circuit via the temperature switch.

The other (LHS) doesn't show anything much, and I assume that is meant to be battery +

I'm thinking ijumper directly from the switch to the RHS, terminal and jumper the LHS terminal to batt +, though I'll bench test the switch with hot water first.

IF this works, what to do about the loom? REALLY don't want to try and re-make that, but it seems a bit risky to just leave it with potential internal shorts..

I'm going to do any further full function testing with the rad cap off to slightly reduce the risk of popping the HG, assuming I havn't already.

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Sun 19 Apr 2020 06:14

Daihatsu Skywing (with stupid owner) - Mains Damage To Car Electrical System - edlithgow

Water around boiling (from a water dispenser, common here) lowers the resistance of the temperature switch to around 70 Ohms, not quite low enough to activate the continuity buzzer (which I have trouble hearing anyway. Need an OLD GEEZER METER with MORE LOUDNESS and BIGGER NUMBERS) but probably low enough to be considered functional,

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Tue 21 Apr 2020 05:58

Daihatsu Skywing (with stupid owner) - Mains Damage To Car Electrical System - edlithgow

I made up a sort of break out box using connectors of tightly rolled beer can aluminium between the relay and its connector block, so I could completely isolate solenoid control from its suspect wiring loom circuit.

I suspected this had an internal short to earth, producing an "always on" condition.

So rigged, the fan came on just as the coolant seemed to be about to boil.

HUZZAH! A victory for punk technology.

Except that it stayed on with engine off and cooling. WHAAT??? The switch is LATCHING???

I suppose its more likely that my half...er...baked breakout box was shorting on the power side, but it didn't LOOK like it was, insulated with tape etc.

I lost patience at that point (I've missed out a lot of prior unedifying and possibly damaging messing about) and made up a manual fan control wire (old mains power lead jumpered at the plug with a 25 amp fuse). I'll try again for inspection like that and then decide if its worth spending more time on. Maybe get an IKEA meat thermometer for temperature warning.

Ironically, after the recent ignition fettling, it seemed to be running unusually well, generating about 22 ins. Hg at idle

After the overheating and miguided emergency responses its down to 16 ins Hg, which I suppose might suggest head gasket or piston damage.

Combined with wiring loom damage and uncertain steering column stalk switch operation, the end of the line seems to loom

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