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Electrical woes


Nelly

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I have posted this here is the woes in question mainly relate to the engine gauge's on my S2 - as you will see.

 

Brief history - I had a rouge overheating problem and Sportomotive in Salisbury fitted a different sender and confirmed the gauge reading was OK with a laser thermometer.  All was well until the hub fell off the water pump on the way home, which took the car off the road again.   

 

That was end of April, and I have now replaced the water pump, filled the system back up - but now my temp gauge does not work.  All I have done is take it apart and put it back together, there is only one wire to the sender and I can't see why it was working then and isn't now?  All the parts other than the pump are the same.

 

Also, my rev counter is very erratic (sometimes it works and sometimes it doesn't), and my oil pressure gauge also doesn't work at all (I would point out its not original, its an electric gauge).  These two problems existed whilst the temp gauge was OK.

 

I have had the binacle out today and all connections look good.

 

The car did get very damp back in January and I had a bad earth which prevented the car starting - could this have any bearing on anything else?

 

Fuel and voltage gauges are fine.

 

How is the best way to test this, bearing in mind I have a multimeter but don't really know what I am doing with it!  I would like to have a shot and fixing before I call someone out who knows what they are doing.  There are a lot of bullet connectors in the engine bay (although the temp sender wire comes straight off the main loom) so should I also look to replace these?

 

Thanks, as always.  The summer is slipping away and I want to use the car for once!

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The gauge will show one extent of its travel with the sender wire earthed (remove the wire and touch it to the block ) and the other extent just disconnected.

If it does this then the wire and gauge are ok and it is either a dirty connection to the sender or a dead sender.

No movement on the gauge suggests a break in the wire or a gauge fault

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There has to be an earth connection, too; if the sensor outer is not earthing properly or there's a bad earth to the gauge, it won't work. Oil pressure gauge...if it works through a capillary tube, i.e. not an electrical gauge, then lack of working is down to gauge failure or a blockage in the capillary tube. Charles has the Instant Diagnosis System for the temperature gauge!!

Scientists investigate that which already is; Engineers create that which has never been." - Albert Einstein

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Check of temp gauge successful.  Took the sender out and put it back in, and its working!

 

Just the oil pressure and rev counter left to sort, and I have no idea at this stage where the points to check are for both of these.  My oil pressure gauge is an electric version (and not the original) so not sure if I will have the tube or not.

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OIl pressure electric gauge..do the same checks as for the temperature gauge, they work the same way. Need connection to the sensor output and a good earth....sounds like the temperature gauge body wasn't earthed correctly; may be the same for the pressure gauge....

Scientists investigate that which already is; Engineers create that which has never been." - Albert Einstein

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Thanks guys.

 

Pete - I have found a photo I took with the carbs removed, and I do have a black tube coming off the block at the point you mentioned,  It then heads to towards the back of the car.  I have booked tomorrow afternoon off work so will check then.

 

Once I find the electrical connection I will then test again.

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Hmm. It should be heading forwards towards the gauges so I guess what ever sender you have will be on the end of it. I'd be inclined to replace the gauge with a good ol' fashion mechanical one but you'd probably need to do the pipe too which is about £20.

 

Good luck.

Pete '79 S2

LEW Miss September 2009

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Thanks Pete.

 

Its an odd one.  The pipe heads to the gearbox, and there is indeed some kind of sender unit at the end mounted on the engine bay cut out.  Its really rusty, and doesn't have any electrical connectors at all.  There was a black wire wound around the top of it, earthed that but no response on the gauge.  By its condition I would say its original but have no idea if it was fitted there originally if the tube should go to the guage.

 

There is a blue and red wire adjacent to it which are not connected (they come off the same part of the loom as the feed to the ignition coil).

 

The gauge did work, but I have no idea what was actually sending it a signal at this stage.  I am going to mail Malc Holmes to see if he can remember...

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EDIT - I have fortunately found an old photo of the engine bay which shows how its connected.  The blue wire I referred to above is fitted to the end, so I think I can sort this one out!

 

I think I know the culprit who removed it (wasn't me, a qualified electrican!)

Edited by Nelly9000
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:thumbsup:

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Temp gauge - not sure, I took the sender out, put it back and it now works!

 

Oil pressure - wire not connected, as basic as that!  I have purchased a new sender as it was only £22 so will be fitting that tomorrow.  I now know why my ignition coil is not in its original location, because Malc housed the electrical sender in its place to keep the oil pipe short (that's why it heads towards the gearbox).

 

Found there is a small coolant leak when I got the car out the garage on Tuesday which I hadn't noticed so getting the system up to pressure has clearly found a weak spot.  Hopefully just some tightening, bleeding the system and MOT next week and I may be heading your way next weekend Pete!

 

I have also had a lot of the interior out and have been tinkering with some bits I wasn't 100 percent happy with when it all went back together a few years back.

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Make sure your coolant leak isn't coming from the water pump before you do many miles.......(!)

Scientists investigate that which already is; Engineers create that which has never been." - Albert Einstein

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Well,,,,,

 

As you know things never run smoothly.  I took the old oil pressure sender off the car on Saturday, it was so rusty that I damaged the adaptor which connected it to the hose, so it wont seal correctly and leaks.  Needless to say, I didn't have one of those so that put paid to that and I didn't get to start the engine because of that.

 

I did do load os work on the car at the weekend.  Most of the interior came out and I have repaired/re-stuck some things and generally did some jobs which needed doing - new connector should hopefully come tomorrow and if it does I will put it on tomorrow.  We are still getting there!

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Hurry up! Going to need my kriket gauge soon...it's cambelt time (well about 2 years overdue!).

 

Found left had engine mount is broken too which might go some way to alleviating the cover problem but not sure.

 

Hey ho...

Pete '79 S2

LEW Miss September 2009

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I'm trying!  I reckon I spent 14 hours over the weekend and another 2 hours this evening.

 

All the interior went back in tonight - I have only done a few tweaks, but it looks brilliant now.  Its really polished it off, I am well pleased with it.

 

Hopefully the hose bit comes tomorrow that leaves me Weds/Thurs night to get her going, and I will try for an MOT on Friday.  Either way, I am happy to drop the gauge up this weekend if you need me to.

 

Not pleased your engine mount has gone, but as you say it at least may explain why you have an issue.  If you need an extra pair of hands to sort it, you know where I am.

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