Jump to content

Electrical Gremlins


Recommended Posts

Hi

Parked up my 4 last week after a good run and when I came to try to start it a couple of days ago the ignition light came on and then went off as I turned the ignition switch and has remained off since then. The battery is only a couple of months old and has a full charge and the terminals are tight, I've checked all the fuses and they're all ok, but replaced them with new. The connections to the starter motor are good and there are no obvious disconnected wires under the bonnet. The loom is old (?original) with various modern additions adding in relays for lights, electric fan and wiper/washers. Any ideas where and what to check before I begin the laborious task of checking through the loom.

Dave 

Link to post
Share on other sites

Not sure whether a '4 has a starter solenoid you can operate manually - but if it has and the starter turns that would show the battery and battery connection are OK. If the horn works, that would show the same I guess.

Try turning on the headlights. If they come on and a drain shows on the ammeter then current is getting through and it is looking like the ignition switch or connections to it may be at fault. 

 

Edited by RobH
Link to post
Share on other sites

Do you have some sort of battery isolator Dave?

such a total loss of electrickery points so something simple !

steve

Link to post
Share on other sites

Could well be a battery terminal.  They may be tight but that doesn't necessarily mean they're making good contact. First thing is to slacken both and wiggle them before re-tightening. Also check the battery earth connection to chassis.  If that doesn't do it , it's not unknown for new batteries to die. 

 

Link to post
Share on other sites

If your battery is really flat, which seems likely, you'll need an old-fashioned charger (selenium rectifier) because, from what I have read on this Forum, the clever modern chargers cannot cope with such a condition.

When my wife left her High&Dry with its ignition turned ON overnight, my meter read 5 volts, but after 24 hours connected to my ancient charger, all was well.  Just as a test, SWMBO repeated the exercise a few weeks later, but the old charger worked its magic again.

Ian Cornish

Link to post
Share on other sites
18 hours ago, DaveB66 said:

Hi

Parked up my 4 last week after a good run and when I came to try to start it a couple of days ago the ignition light came on and then went off as I turned the ignition switch and has remained off since then. The battery is only a couple of months old and has a full charge and the terminals are tight, I've checked all the fuses and they're all ok, but replaced them with new. The connections to the starter motor are good and there are no obvious disconnected wires under the bonnet. The loom is old (?original) with various modern additions adding in relays for lights, electric fan and wiper/washers. Any ideas where and what to check before I begin the laborious task of checking through the loom.

Dave 

Hi Dave,

I had similar symptoms last year. It turned out to be the socket on the loom going into the back of the alternator.

If you have an alternator pull the socket off, make sure it is physically OK, clean all the contact areas.

 

Roger 

Link to post
Share on other sites

Hi

Thanks for all the various suggestions. I've been out and done some checking with my multimeter on the under bonnet circuits. The battery has a good 12.8volts and this remains the same across the earth point on the body and the end of the feed to the solenoid. There's a slight drop to 12.1v across the fuses and similar from the voltage regulator outputs, it's still running on a dynamo. 

I think that the next step is to get at the wiring behind the dashboard

Link to post
Share on other sites

The puzzling thing is having nothing electrical work, no horns, no lights. It sounds as though the ammeter is connected OK as you have voltage getting to the regulator which is something, but that should then enable the lights and horn at least.   

Remember though that digital multimeters can lie to you by showing voltage where there is actually a bad connection. They don't draw enough current to properly test the circuit. A light-bulb is better for that. 

 

Link to post
Share on other sites

Hi Dave,

well done! You have two possibilities now.

1 st:

'"All" current with the engine off goes the way from the battery - through the ampere meter - to terminal A of the regulator.

Measure next the voltage from terminal A to ground, please.

2nd:

Indeed not all current goes this perhaps faulty way, the starter is direct connected to the battery by the starter relais.

Press the manual button on the starter relais and see what happen.

Ciao, Marco

Edited by Z320
Link to post
Share on other sites

As Marco says, all the power on the 4a, except starter goes through the ammeter, but the terminals on the ammeter are not easily accessible without taking the glove box out and pulling the ammeter forwards after removing its fixing bracket. Because of this the ammeter gets no maintenance and the terminals go rusty. Remove the heavy wires and give everything a good clean. 

Chris

Edited by ChrisR-4A
Link to post
Share on other sites

Thanks once again.

Marco - the voltage across the A terminal of the regulator is 12.1v

Chris - I'll tackle the ammeter when I can get time in the garage.  It probably needs a good clean as my 4 is an early one (mid Jan 62) and still has it's original long needle gauges, also it's next to the speedo so should be reasonably accessible. 

Dave

Link to post
Share on other sites

I'm not sure about that Roger. The voltage on the A terminal that Dave measures is suspiciously low at 12.1. There should be no difference between that and the 12.8 measured at the battery, when measured with a multimeter which draws next-to-no current. That suggests a bad connection somewhere between the two and the ammeter is prime suspect. 

As I keep pointing out, a multimeter is not a good tool to use for fault-finding on a car. It draws no current and can fool you into thinking there is a good connection when in fact there isn't.   A sidelamp bulb with two wires on it is more useful when checking whether current is getting where it should because it draws enough current to show if there is a bad connection. 

Link to post
Share on other sites

Hi Dave,

what did the starter when you pressed the button of the starter relay? If you did not, please press it.

I would do nothing on the car until we / you are sure what the issue is. Allow me this: we are not at that point now.

You have 12.1 V on terminal A1 AND 12.1 V on the fuses - the regulator to me seams not to be the problem.

And the ampere meter probably also not.

Ciao, Marco

Link to post
Share on other sites

I suggested that test right at the beginning Marco and I think the answer was that it didn't work. (posts 2 and 3 on Saturday)

I'm not sure whether Dave has actually tested the battery on a load rather than just with a multimeter.  If not it could still be that the battery is faulty but reads OK without any current drawn. 

Edited by RobH
Link to post
Share on other sites
3 minutes ago, RobH said:

I'm not sure about that Roger. The voltage on the A terminal that Dave measures is suspiciously low at 12.1. There should be no difference between that and the 12.8 measured at the battery, when measured with a multimeter which draws next-to-no current. That suggests a bad connection somewhere between the two and the ammeter is prime suspect. 

As I keep pointing out, a multimeter is not a good tool to use for fault-finding on a car. It draws no current and can fool you into thinking there is a good connection when in fact there isn't.   A sidelamp bulb with two wires on it is more useful when checking whether current is getting where it should because it draws enough current to show if there is a bad connection. 

The ammeter coil has been known to become disconnected. Perhaps it is only just touching at one end.

 

Roger

Link to post
Share on other sites

Hi

Thanks once again for the suggestions.

I've been out and swopped the battery over for the one from the TR6, that I know is working, and the situation remains the same in the TR4. The one out of the 4 runs all of the circuits on the 6 and starts it OK. So I think I can now discount the battery.

Came in for a cup of tea, it's bitterly cold here today, before going out to tackle the ammeter.

Link to post
Share on other sites

Dave,

You said:

“My 4 does have remote starter solenoid and it doesn't work either, although it did.”

 

Bit ambiguous I’m afraid.

Do you mean that you pushed in the starter solenoid by hand (Big rubber button on end – unless it is a more modern solenoid)?

 

The power from the battery to the starter motor is direct; it only goes through the solenoid. No regulator/ammeter/dash wiring involved.

If the motor does not turn you have eliminated a lot of possibilities.

 

I’m a bit worried about saying this in case I get shot down by the health and safety bods, but…

 

In the old days, I (and I guess many others) would short out the starter solenoid with a big spanner. (Just across the two big terminals.)

You will get a big splash and maybe a bang and the starter motor would turn. If not it usually meant that a battery terminal was dirty.

I’m not suggesting you do this, (unless you feel confident) just mentioning that it is a “Back street” way of testing things.

 

 Charlie D

Link to post
Share on other sites
1 hour ago, Charlie D said:

The power from the battery to the starter motor is direct; it only goes through the solenoid. No regulator/ammeter/dash wiring involved.

If the motor does not turn you have eliminated a lot of possibilities.

 Charlie D

Charlie got it, this is my idea.

And it would safe you a lot of work if the starter does not run when you push the button.

Than the issue is the cable from the battery to the starter relay - or the cabel from the battery to the car body.

Link to post
Share on other sites

Dave,

 

I built my own loom, so I can’t be 100% that what I’m about to say is correct, but I think that the feed from the battery to “The rest of the car” comes off a push-on connector on the battery side of the starter solenoid. If there was a problem with this connector (Wire into connector push-on or where the blade is bolted to the solenoid) then no power would get to any other part of the car.

Along with a dirty battery connector I have had problems with the solenoid connectors as well

As Rob said, don’t think that just because you get a voltage reading in various places on the car that the battery connector is not dirty. The larger current drawn by normal items may cause a connection to break down..

DON'T play with the ammeter just yet. Once you start to get your hand in behind the dash you may end up with more problems than you could ever imagine. Leave that as a last resort.

Charlie.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.