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Urgent Electrical problem - wedding Friday

tony298
Posts: 3
Joined: Tue Nov 28, 2017 3:39 pm
Location: Hampshire. UK.

Re: Urgent Electrical problem - wedding Friday

Post by tony298 »

A simple way to test the starter motor.
Check that the cable terminal on the starter motor is clean and tight.
Remove the starter motor cable from the solenoid and connect one end of a jump lead to the cable ring terminal.
Wrap it in cloth or similar so that it cannot short against any metal part.
Touch the other end of the jump lead to the live battery terminal, positive in your case as yours is negative earth.
If the starter turns it is ok, if not, there is the problem.
Doing this bypasses everything in the starting circuit and feeds 12 volts direct to the starter motor.

KV8
Posts: 304
Joined: Sun Mar 06, 2016 7:05 pm
Location: Cambridgeshire

Re: Urgent Electrical problem - wedding Friday

Post by KV8 »

Thanks, however I would be concerned that the clip on one end of the jump lead would become welded to the positive battery terminal?
The push button solenoid definitely connects battery to starter ( all other connections to solenoid removed) and nothing happens at all except battery voltage drops to zero!

H

bakergh
Posts: 109
Joined: Wed Feb 24, 2016 1:57 pm
Location: New Forest, Hampshire

Re: Urgent Electrical problem - wedding Friday

Post by bakergh »

If the battery voltage is falling to zero when measured at the solenoid as it is pressed it points to either a bad connection between the battery and the solenoid or the battery cannot deliver the required current for the starter motor. I think you would weld the solenoid shut if you pressed it with a short circuit on the starter motor side. I would disconnect the battery and reconnect it making sure that you have two good clean contacts. If no joy have the battery tested. It is quite common for batteries to suddenly fail in the manner you described. It may appear to charge ok and be able to supply enough current for headlamps etc but this does not mean it is cable of supplying enough current for the starter motor.

Graham

KV8
Posts: 304
Joined: Sun Mar 06, 2016 7:05 pm
Location: Cambridgeshire

Re: Urgent Electrical problem - wedding Friday

Post by KV8 »

Thanks

Sure connections and battery are OK as with starter disconnected at solenoid get 12.8V at starter lug on solenoid when push operated. However take your point have got a good spare battery and will Jump this later today with original battery disconnected. Meter gives zero (0.000) ohms between Starter feed an earth.

Regards

H

Sydsmith
Extremely Wise Man
Extremely Wise Man
Posts: 1369
Joined: Sun Feb 14, 2016 11:15 pm
Location: Aberystwyth Wales

Re: Urgent Electrical problem - wedding Friday

Post by Sydsmith »

Sorry KV8 I know you say the battery is OK but think again, if the starter was short circuit to the degree the battery voltage died completely you would see a lot of smoke from the starter or at the very least it would get very hot.

If you have no smoke or the starter does not get hot you have either a duff battery which collapese under load or you have a duff connection somewhere.

Press and hold the button for about 30 seconds or so that should either heat up the starter produce smoke from ity or if you have a duff connection the connection will get hot or at least warm.
Hope that helps. Syd

bakergh
Posts: 109
Joined: Wed Feb 24, 2016 1:57 pm
Location: New Forest, Hampshire

Re: Urgent Electrical problem - wedding Friday

Post by bakergh »

The starter motor is a high current device and therefore has a very low resistance when measured with a multimeter.
You would appear to have a high resistance in the starter motor circuit causing the measured voltage when the solenoid is pressed to drop to zero. The voltage is being lost across the faulty connection. Are you sure you have a good negative connection to the engine block. Is the earth bonding cable present and well connected. If the cable is damaged or missing the return connection is made via the choke cable which can work for some time before you see a problem.

Graham

KV8
Posts: 304
Joined: Sun Mar 06, 2016 7:05 pm
Location: Cambridgeshire

Re: Urgent Electrical problem - wedding Friday

Post by KV8 »

Amazing

Thanks.....

OK Connected spare battery direct to solenoid and earth with jump leads and lo and behold starter turns! Try again with fitted battery - nothing. So tried connecting fitted battery+ve to solenoid with jump lead and starter turns! But just a minute says I - jump lead was clipped to +ve connector not battery post. So conclusion is that battery to solenoid lead has a partial break somewhere. To conclude I waggled the Battery +ve lead about and then re-tested and all then OK but only perhaps until the Bride gets in car ...!?

Also have remaining ignition switch problem which was also throwing red herrings. I had in my long term "might be useful one day" box a possible ordinary switch. Connected can turn ign on and off and start car from dashboard but switch is too small to mount on dashboard.

So hoping local motor factors can supply replacement battery terminal to solenoid cable with correct ends and larger toggle switch as temp replacement for ign switch.

Given this DV8 might still grace the day!.

Very many thanks to all who have responded and helped to find this rather unexpected fault which was confused by the problems with the ign switch at the same time.

Regards

H

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John-B
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Location: Salisbury, UK
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Re: Urgent Electrical problem - wedding Friday

Post by John-B »

As a back-up in case the starter doesn't work "on the day", you should do what I did with my Escort (a negative earth car).

The ignition switch turned on the ignition, but the starter spring connection in the switch occasionally didn't work, then stopped altogether.

I got some 13A household cable and connected to the positive starter terminal. I made sure the car was in neutral and held the loose end of the cable to the positive battery terminal as long as necessary. A few minor sparks but the starter worked perfectly.

While driving I left the cable connected to the starter but the other end loose in the engine bay for use as required.

It may have been a 30A cable I used, or I may have twisted all three wires of a 13A cable together to get a good capacity, but I can't remember.

Be careful which terminals on the starter and battery you use. For a negative earth car it's easy, positive starter terminal to positive battery terminal, but for a positive earth car would it be negative starter terminal to negative battery terminal? I'm not sure.

tjt77
Wise Man
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Posts: 525
Joined: Wed Mar 23, 2016 7:01 pm

Re: Urgent Electrical problem - wedding Friday

Post by tjt77 »

the problem may well be your starter .. but its well worth double checking battery connections at the actual battery.. its really does not take much for the terminals NOT to pass current through ..I had a similar ongoing problem regarding loss of all power when pressing the starter button..in spite of the fact that I'd cleaned the battery terminals several times.. the issues was in fact the battery terminals not connecting properly..
also ;- if you want to improve things by 'upgrading' the current starter for a modern design one that spins the engine faster and uses less current.. (and is both smaller and lighter hence easier to fit) the 'gear reduction' starter for an Austin Healey 100/6 or 3000 will fit the Daimler 2 1/2 litre saloon..

KV8
Posts: 304
Joined: Sun Mar 06, 2016 7:05 pm
Location: Cambridgeshire

Re: Urgent Electrical problem - wedding Friday

Post by KV8 »

[quote=tjt77 post_id=20417 time=1529694372 user_id=363]
the problem may well be your starter .. but its well worth double checking battery connections at the actual battery.. its really does not take much for the terminals NOT to pass current through ..I had a similar ongoing problem regarding loss of all power when pressing the starter button..in spite of the fact that I'd cleaned the battery terminals several times.. the issues was in fact the battery terminals not connecting properly..
a[/quote

Please read my last post 3 above and you will see that as suggested by previous posters this course of action had already been tried but using a jump lead found the source of the problem.

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