Indicators not working and Positive earth

Technical advice Q&A

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Tony
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#1 Indicators not working and Positive earth

Post by Tony » Mon Oct 12, 2020 12:15 pm

Ok, being a bit dim here but i am going to ask anyway.
My indicators are not worKing so i first went for changing the flasher unit. Still not working.
My car is positive earth so started Checking i had a supply to the flasher unit unit.
Now assuming i am thinking right if i put my multi meter on the supply side of the flasher unit and earth the other probe to the body i shoukd get 12v. I don't get any thing. If i stick one probe on fuse 7 (i think supplies the flasher unit) and the other to earth i should get 12V . I don’t get anything.

If i check the voltage across the battery i get 24c ???.
If i check the voltage from the - post the the body I get 24volts.

What am i doing wrong or do i just not understand the whole positive earth concept.

Any advice would be appreciated.

Tony
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Jack the lad
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#2 Re: Indicators not working and Positive earth

Post by Jack the lad » Mon Oct 12, 2020 12:42 pm

Hi Tony,
not wanting to appear clever, I think your problem is your use or mis-use of the multimeter. You can get a very cheap book that should make it all clear, "How to use your multimeter" is a good starting point.
You need to be aware of the relationship between Volts, Amps. and resistance. You could already have damaged your meter if you used it on the wrong scale, the good news is you will not have damaged your car. cheers John. (retired Fujitsu electronics engineer)

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MSM
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#3 Re: Indicators not working and Positive earth

Post by MSM » Mon Oct 12, 2020 12:46 pm

Tony wrote:
Mon Oct 12, 2020 12:15 pm


If i check the voltage across the battery i get 24c ???.
If i check the voltage from the - post the the body I get 24volts.

What am i doing wrong or do i just not understand the whole positive earth concept.

Any advice would be appreciated.

Tony
Tony - I suspect your meter is either faulty or set incorrectly. A 12 V battery will read 12 V irrespective of being positive or negative earth.

Check the settings of your meter and get youself a wiring diagram to be certain of which fuse supplies the flashers.

Kind of agreeing with John who beat me to a reply!!
Mike

S2 FHC

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Tony
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#4 Re: Indicators not working and Positive earth

Post by Tony » Mon Oct 12, 2020 1:49 pm

Hi guys, thanks for advice and no offence taken. I have the multi meter set to the 0 - 200 volts and appreciate the difference between Volt, amps and less sure about resistance. I think my meter must be faulty as I have used the meter for a number of years with no problem. What made be me less sure was the positive earth Issue and if that was causing me to mis -read the situation.

I presume i am right that the body of the car is positive and the all the wiring is negative apart from earth wires.

If i ignore the muti meter and and run a wire from fuse 7 to the the body of the car (With a bulb in the line ) It should light up confirming I have a supply.

Tony
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#5 Re: Indicators not working and Positive earth

Post by rswaffie » Mon Oct 12, 2020 2:13 pm

Hi Tony,
I’m assuming you have a 3.8 given the positive earth config.
If the wiring is standard, then there should be a switched power feed from the ignition switch (white) to fuse 7. Then a green from the other side of the fuse to your flasher unit. I believe this also feeds the choke and low fuel lights as well - are they working?
With the battery disconnected, Use your multimeter in ‘continuity test’ mode from the live side of the fuse 7 to the connection at the flasher unit first. That will rule out bad fuse/wiring. Depending on the result, tou can plan your next test.
Richard

S1 3.8 FHC Opalescent Golden Sand with Tan Trim 889504
Now running-in my diy nut ‘n’ bolt restoration. :wrench: :hammer: :fingerscrossed:

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#6 Re: Indicators not working and Positive earth

Post by mgcjag » Mon Oct 12, 2020 2:18 pm

Hi Tony...fuse 7 is only live with the ignition on......yes a bulb from fs7 to the body will light....when ignition is on....pos or neg earth.......the only real difference is which terminal of the battery is connected to the car body..so if pos terminal goes to body then you have a pos earth car and vis veresa......Indicators/flasher is always very tricky to check with a meter.......a blown bulb on one side can stop the other on that side working....or a bad earth one side can do the same.....check your bulbs....Steve
Steve
1969 S2 2+2 & Building a C type replica

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#7 Re: Indicators not working and Positive earth

Post by Tony » Mon Oct 12, 2020 3:51 pm

Ok , thanks again everyone. I have decided my multi meter is bust as it is giving 24-25 v across the batter terminal.
I have checked the supply to fuse 7 with a test bulb and it lights, so i have power. I jumped a lead from fuse 7 to the flasher unit direct and the flasher unit and indicators work. Noted the direction signal light Indicators on the dash are not work. Need to check them. So it seems to suggest the link from fuse 7 to the flasher unit is broken. So progress is being made. So now need to find where the link is broken. As it goes into a harness that is proving difficult with limited room. I will check the other items that work of fuse 7 to see if they are working . I will continue to bore you with my progress.

Thank again for the advise.
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rswaffie
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#8 Re: Indicators not working and Positive earth

Post by rswaffie » Mon Oct 12, 2020 4:58 pm

Not boring Tony - problems with indicators seem to pop up quite regularly on the forum so it’s always useful to see how they are tested and (hopefully) resolved.
Looking at the wiring diagram, it looks like there is a double bullet connector that takes the green wire live feed to the flasher, choke and fuel warning lights. It may be a bad or dislodged connection there.

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Richard

S1 3.8 FHC Opalescent Golden Sand with Tan Trim 889504
Now running-in my diy nut ‘n’ bolt restoration. :wrench: :hammer: :fingerscrossed:

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#9 Re: Indicators not working and Positive earth

Post by Tony » Mon Oct 12, 2020 5:53 pm

Hi RSwaffie,

Just came back in from the garage and have drawn the same conclusion as my wipers, coke light, screen washer, flasher unit do not work but the the fan motor does. The problem now is i cannot find the connection you have circled. It must be behind the speedo / rev counter panel. I will have to remove the instrument panel or maybe get access from the top by removing the top dash panel. The little begger Is hiding in there somewhere
but doing a good job avoiding capture.

Thanks again.

Tony
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#10 Re: Indicators not working and Positive earth

Post by rswaffie » Mon Oct 12, 2020 6:22 pm

Hi,
You might be able to get at it by removing the underdash trim panel either side of the steering column that are normally held in place by self tappers. I seem to remember that there are a whole load of single and double bullet connectors that get tucked into the bulkhead on the steering side of the car.
Richard

S1 3.8 FHC Opalescent Golden Sand with Tan Trim 889504
Now running-in my diy nut ‘n’ bolt restoration. :wrench: :hammer: :fingerscrossed:

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#11 Re: Indicators not working and Positive earth

Post by Jack the lad » Mon Oct 12, 2020 6:39 pm

Hi Tony,
before buying another multimeter please check that you have not selected the A.C. range as we use D.C. on our cars. Check that its internal battery (usually a 9 volt PP9) is good and whilst the battery cover is off look for a couple of fuses and check them out. cheers John.

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#12 Re: Indicators not working and Positive earth

Post by mtnjag » Mon Oct 12, 2020 10:40 pm

Was just in there on my 3.8. Yes, as mentioned the double to one connector should be accessible by removing the Trim panel. It should be right next to the multi pin(5 i think) coonector. They’re just tucked up there.

I thought my flasher was bad too, and my plastic spring had also broken. Turned out that along with the spring breaking the switch had loosened up as well and was not making proper contact on the little dome contact points.

New plastic “W”, a tightly peened rivet, cleaned and lubed contacts with dielectric grease and all works well with the old and new flasher.
Layne
Car #876005, 62 OTS

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#13 Re: Indicators not working and Positive earth

Post by Tony » Tue Oct 13, 2020 10:52 am

At last i have solved my problem. Whoever wired my car went off plan and wired my indicators, coke light etc to fuse 6 Instead of fuse 7. Fuse 6 was fused and as the clear section was facing away from me I did not notice it. OK my fault for not spotting it but we live and learn. I notice fuse 6 is 35 amp and fuse 7 is 17amp.. should i start changing it all around or leave things alone ad they have been like that since I bought the car 10 years ago with no problems.

At least i can now move on and kick myself for not spotting the blown fuse.

Thanks again everyone for you help.

Tony
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#14 Re: Indicators not working and Positive earth

Post by christopher storey » Tue Oct 13, 2020 11:23 am

Tony : be careful about the fuse ratings, because they can be a trap for the unwary . British ratings are blow ratings, and your 35 amp fuse will blow at 35 amps load, but is only designed to carry about 50% to 60% of that load continuously. American ratings are continuous load, and your 17 amp fuse is probably American rated . Usually, British fuses are glass, and Euro/American are solid. What you must NOT be tempted to do is to replace a 35amp glass fuse with an American type of say 30 amps . Without wishing to teach my grandmother, etc. you can calculate the likely load on a circuit by using the formula Watts /12 = amp loading. So, the indicators on their own, which are likely to be 21 watts each = 42 watts , producing a load of 3.5 amps . The same fuse also usually should carry the warning lamps, the reversing lamp, and the wipers so with all these in operation you are probably talking about a total continuous load of perhaps 12 amps, thus requiring a blow rated fuse of at least double that

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#15 Re: Indicators not working and Positive earth

Post by Tony » Tue Oct 13, 2020 2:21 pm

Hi Christopher, thanks for the heads up on the fuse sizes. My fuses are all clear class type. ( so assume are the English type)

I remove all the cables from fuse 6 which had blown and put them back on one by one untill the fuse blew. It looks like the wiper motor is causing the problem as it is the only thing not working with that cable disconnected.

A bit rough and ready way of finding out but everything else is now working. I now need to find out why this is happening.

I also need to by some English fuses.

PS. People of a Nervous Disposition need to look away

Tony
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#16 Re: Indicators not working and Positive earth

Post by mtnjag » Tue Oct 13, 2020 2:27 pm

The standard old style US Buss fuses are clear glass. Still a standard item in auto parts stores. They typically have the rating stamped on the end cap .They are not slow blow. They are same size as the english fuses.

The slow blow fuses i get here, as well as my originals, have a paper slip inside indicating the rating.
Layne
Car #876005, 62 OTS

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#17 Re: Indicators not working and Positive earth

Post by Gfhug » Tue Oct 13, 2020 4:53 pm

Tony, you might try searching for Unipart car fuses or British Leyland, eg:
https://www.ebay.co.uk/itm/5-Pack-of-25 ... SwfcBZkrJI

Geoff
S2 FHC Light Blue
S2 OTS LHD - RHD full restoration

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#18 Re: Indicators not working and Positive earth

Post by Tony » Wed Oct 14, 2020 1:10 pm

Hi, just to push my luck has anybody have any thoughts on my wiper shorting to earth. I have checked the supply up to wiper motor and it is not shorting up to there. So i am assuming it is withIn the motor or the wipe switch.

Before I take ofF the motor is there any test i can do on the motor to see if it Is working or has a fault. I suppose it could be in the switch with 6 wires coming of the switch i am not sure where to start.

Tony
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#19 Re: Indicators not working and Positive earth

Post by Heuer » Wed Oct 14, 2020 1:35 pm

Start by reading this from our Knowledge Base:
S1 Wiper motor operation guide: https://www.dropbox.com/s/x7f9u2g650up8 ... l.pdf?dl=1

Counter intuitively the motor is always 'live' when the ignition is on, the wiper on/off switch earths the motor causing it to run.

Tip: When you remove the motor (if it is the motor at fault) you will need to remove the special snaplock from where the primary link attaches to the wiper link assembly. You need to drop the centre instrument panel to get at it but before trying to unlock it push some dusters in there as it can be a slippery little sucker and easily fall into the bowels of the bulkhead. The dusters will catch it if/when you fumble it!
Image

You can't buy the snap-lock separately so you will need to buy the whole assembly and that means having to adjust the primary link to get the wipers working properly so take your time.
David Jones
S1 OTS OSB; S1 FHC ODB

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#20 Re: Indicators not working and Positive earth

Post by Tony » Wed Oct 14, 2020 4:35 pm

David, Thank you for the advice regarding the clip, i shall make sure not to lose it, At the moment i am trying to isolate where the short is. i have checked each wire up to the motor and all seem ok. i have now disconnected all wire to the motor and pulled all wires from the wiper switch. the only wire that my still be connected is to the limit switch which i have not found just yet.

On testing each wire going into the motor for shorts to earth, then this shows the blue wiring and the green wire are connected to earth. not sure this should be happening and wondering if this could be the problem.
if anybody knows how the these motor work and direct me to a solution it would be appreciated.

Tony
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