Lotus Elan

Help please. Intermittent fail.

PostPost by: Galwaylotus » Sun Jul 12, 2015 4:15 pm

I was warming up my Elan's engine to go for a run the other day when it suddenly quit. I restarted it and a short while later it quit again. After that nothing worked, no starter, even the window switches which are live always. As I was unsure of the connections on the back of the ignition switch I thought it was a faulty switch. Having subsequently removed the switch I discovered that the two terminals at position 1 (+12V and the cable to the window switches) are in fact common. Meanwhile I rigged up a toggle ignition switch and a momentary switch for the starter and tried, today, to run by bypassing the ignition key switch. I got the engine started, switched it off and tried to restart - nothing. Everything dead. I have 12.5V at the NU cable that supplies the ignition switch and even moving it around I never lost the 12V so I don't believe the supply voltage is bad. At one point I thought the fault might be in the ignition warning lamp circuit but disconnecting that didn't resolve the problem.
I ran the following checks:

All switches off - +12V @ NU cable
White lead supplying the fuse box connected (electric fuel pump supplied from fusebox) - voltage at NU 1.6V
White leads supplying ignition coil and ignition warning lamp respectively connected - voltage at NU 1.3V
Start (White/Red) cable connected - voltage at NU 0V
Please note that nothing was working in any of the above states but those were the voltage readings I logged.
Interestingly when I got no response the other day I left it alone and did get an early response today but later got nothing.

It certainly seems like a bad earth somewhere but I'm stymied on where to start looking. Has anyone seen anything like this before - and resolved it? :? :cry:
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PostPost by: steve.thomas » Sun Jul 12, 2015 7:27 pm

Had a similar situation a few years ago which turned out to be the main battery earth connection to the chassis under the boot floor. Mine was finger tight only! I check it periodically now, and it always manages to get loose over about 6 months. Others on here have modified the connection to be at the rear chassis towers.
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PostPost by: elansprint71 » Sun Jul 12, 2015 7:40 pm

Agree- almost certainly a bad earth (or two)... somewhere.

One thing I have learned in 40 years of Elan ownership- you can add lightness anywhere- except where earth connections are concerned. Earth everything, strip and clean every couple of years. Good luck.
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PostPost by: Galwaylotus » Sun Jul 12, 2015 7:42 pm

Thanks, Steve. I'll check that out. It seems that I always had 12V at the switch input though (between NU cable and heater casing) but perhaps I didn't check it at the time of failure. Il go through the wiring diagram again to see if anything stands out. My wiring seems to be a cross between the S1/S2 diagram and the S3 diagram so it's always a challenge. In addition there are a few modifications due to conversion to an alternator, electronic ignition and Stealth BlackBox wiring etc.!
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PostPost by: Galwaylotus » Tue Jul 14, 2015 8:22 pm

I spent some time today searching for the electrical fault and I don't see a bad earth. Here are my (long) notes on today's investigation. More checks tomorrow, weather permitting.

Resistance checks (earth at cockpit earth point):
? W to fuse panel 118.5?
? W coil and ign warn lamp 2870?
? WR starter solenoid <1?
? P horns 761?
? N window switches ?? (no connection)

Voltage checks (earth at cockpit earth point):
? NU to cockpit earth 12.61V
? Battery disconnected 12.61V
? Battery connected 12.61V
Conclusion: cockpit earth is good.

Check:
1. NU to WR Nothing else connected.
o Starter turns at first attempt.
o 2nd attempt ? no starter. Still voltage at NU. Still 0? WR to cockpit earth.
2. NU to N (window switches)
o No response. Still 12.6V at NU.
3. NU to W (fuse box)
o 1.86V @ connector block (NU) and at fuse box ?in? terminal.
I then wiggled the red cable from the fuse box to the cigar lighter and the fuel pump started.
Disconnected the red cigar lighter cable and the starter worked. I connected the ignition cables and BlackBox and started the engine but it soon cut out after which the starter no longer turned. NU still had 12V with the ignition switch off but 1.3V when switched on (WR and W - Coil/Lamp) connected.
With only the starter (WR) connected to the temporary switches there was 12V at NU when switched off and 0V at NU when switched on (Momentary starter switch both cases).

With all systems ?dead? I then disconnected the battery earth cable and reconnected it. With only one cable at a time connected to NU these were my observations:
1. WR connected to NU ? Starter works
2. N connected to NU ? Windows work
3. WR connected to NU ? Starter works
4. W (fusebox) connected to NU ? pump works
5. WR connected to NU ? Starter works
6. Parking lamps front and rear worked.

It seems whatever the fault, it resets if the battery is disconnected.

If I had much hair left I'd be tearing it out now! :? :shock:
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PostPost by: Craven » Tue Jul 14, 2015 10:14 pm

Hi,
Previous owner of my car had starting problems, went down the usual route of checking all earths even went to the extremes of a power cable direct from battery to starter motor fixing.
Eventually I found the problem; it was an internally corroded POSITIVE battery connector, looked fine on the outside but had serious oxidisation between the strands and the inside of the connector.
There?s always the possibility of a faulty battery, I have seen an intermittent connection, at starting currents, between the post and internal plate arrangement.
May help
Ron.
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PostPost by: mbell » Tue Jul 14, 2015 11:23 pm

I've had issues with everything working fine until you try and start the car. Like Ron it turned out to be poor connection at the battery between the cable and battery connector.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: Galwaylotus » Wed Jul 15, 2015 4:26 pm

This will be a long posting but I hope someone sees something that can direct me toward a root cause. I went back to basics today and took resistance and voltage measurements to see if anything raised its ugly head.

15/07/2015: Decided to go back to basics today. I left the battery disconnected and took resistance measurements through various cables firstly to the cockpit earth and then from terminal to (disconnected) terminal on individual cables.

Cockpit earth to battery negative cable 0?
Cables at ignition switch to cockpit earth:
? W (fuse panel supply) 117.2?
? W (coil and ignition warning lamp) 2863 ?
? WR (starter solenoid) 0.3?
? P (horn & ?) 4 M?
? NU (ignition switch supply from batt via starter) ??
? N (supply from NU to window switches) ??

Resistance at each end of cable (disconnected from all):
? W (coil) 0.6 ?
? W (ign warn lamp to joint at NY 5.3 ?
? W (fuse block supply) 0.6 ?
? NG (from NY ign warning to alternator) 0.4 ?
? W (ign lamp and coil) to NG (alternator) 5.8 ?

Stealth BlackBox cables:
? Black to cockpit earth 0 ?
? Red to connection at fuse panel 0.4 ?
? Green to distributor 0.4 ?
? White to coil (cable extension is UB at coil) 0.4 ?

Next I connected the battery and checked voltage at the battery and at the ignition switch. Measured at 12.59V. Now I connected the starter switch and nothing else and tried to operate the starter. It worked. I repeated twice more but on the fourth attempt there was no response. There was still 12.48V at the switch and the same at the battery.

Some had suggested there could be a battery fault so I replaced the battery with my spare (12.42V at installation) and tried the starter again. No response. I still had 12.41V at the switch. I tried connecting the NU to the N (power to the windows) and they did not operate even though there was 12.41V at the switch.

I measured 12.41V at the starter switch when the switch was open but 0V when it was closed.



Voltages at the window switch input
R.H Switch
? Open 12.41V
? Close Up 0.047V
? Closed Down 12.39V
L.H. Switch
? Open 12.41V
? Close Up 0.037V
? Closed Down 0.030V


Tried the starter again ? no response. Switch open 12.41V; switch closed 0V.

The parking lamps which are fed directly from the battery via the starter solenoid and not through the ignition switch.

With the system still ?dead? I remeasured the resistance between the ignition switch WR to cockpit earth at 0.4? - no change.

Conclusions:
1. Cockpit earth is good.
2. Battery is good (no difference even with replacement).
3. Stealth BlackBox ignition controller and Powerspark ignition module are not the cause (neither was connected during today?s checks).

:?
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PostPost by: EPA » Wed Jul 15, 2015 6:45 pm

Hi
You don't say (unless I have missed it) if the starter turns if you manually press the starter solenoid ie bypassing the starter switch.
If it does turn then the problem is unlikely to be the connections to the battery and chassis at the battery end.
In this case I would be looking again at connections in the cabin,especially the earth.

If it doesn't turn then I would try checking the voltage between the input to the solenoid from the battery and the engine. If it is 12v then continue to monitor and push the solenoid again to see if the voltage radically changes,if it does then the probable cause is the connections at the battery end or the cable lugs on the cable from the battery.

If the problem is a bad connection the readings you get from a modern multimeter can be deceiving because these meters draw negligible current and the resistance/voltage reading can vary depending on the current passing through the bad connection.it is often more revealing to measure the voltage across connections at the time the fault exists eg if you measure the voltage from the ground terminal of the battery to any of the ground cables fed from the cabin ground point there should never be anything but a minute reading.If there is a significant reading then you have a bad connection.

I hope this makes sense and is of some help

Good luck
Ed
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PostPost by: Galwaylotus » Wed Jul 15, 2015 8:45 pm

There is negligible resistance between the battery earth cable and the earth point in the cabin. I've measured this on multiple occasions and the result is always the same.

I don't have a remote solenoid in the engine bay. The only way to energise the starter is through the WR cable connected to the ignition switch. The starter is a "high torque" pre-engaged type with integral solenoid.

There was 12.4V at the starter switch when the switch was open and 0V when the switch was closed. The voltage was measured between the input to the starter switch and the cockpit earth.

I took out the ignition switch before these checks thinking it was faulty. I rigged an ignition switch and a starter (momentary) switch to run the tests and the results are the same as when I was going through the standard ignition switch.
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Kelsport Pre-Engaged Starter
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PostPost by: EPA » Wed Jul 15, 2015 10:36 pm

Out of interest have you ever measured the current drawn by the solenoid on the starter motor?
I would have thought that it could be higher than the rating of the starter switch,it could certainly be higher than the original solenoid.
I have one of these starters on my car but I retained the original solenoid and used it as a relay just in case the current was too high for the switch but I have never actually measured it
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PostPost by: Galwaylotus » Thu Jul 16, 2015 3:34 pm

Raining today so I can't get out to check but I have the problem with both the original ignition switch as well as a heavy duty momentary toggle switch I substituted for the original switch.
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PostPost by: bob_rich » Fri Jul 17, 2015 8:03 pm

Hi

I note you appear to have a pre engager type starter. The pull in for the combined pinion drive /starter relay in is very high. On my wasp unit at 11V the relay/engager draws 35A. I would expect you unit to be similar. Like one of the other posts I kept the starter solenoid to operate this relay and use a direct connection from the battery to the motor high current terminal . The ignition switch then operate the starter solenoid as normal. Could it be the starter switches U R using dont like 35A? after 1 or 2 shots it overheats and then goes high resistance maybe?

Also when checking resistance of connection I prefer to pass current though the terminal from say a second battery or a battery charger feeding say head lamp bulb this give a round 5 to 7A then use the DVM to measure the voltage across the terminal. this should be only a few mV at most. this gives a trued idea of resistance

Hope this helps best of luck

Bob
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PostPost by: Galwaylotus » Fri Jul 17, 2015 8:47 pm

I suppose that's possible except for two things. I have seen the fault with the original ignition switch and the same with my test rig. (See photo) The terminal on the toggle switch in the upper left attaches to the NU cable that supplies 12V always. The switch in the box is the momentary toggle used to supply the starter solenoid via the WR cable. When I last ran the checks, with nothing else connected, as soon as the fault occurred I checked the voltage between the terminal block in the photo and the cockpit earth with the starter switch open and with it closed. Open showed 12V between the terminal block and earth. Closed showed zero V. That, to me, indicates the switch contacts are making.
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Test rig to simulate standard ignition switch.
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PostPost by: bob_rich » Sun Jul 19, 2015 8:45 am

Hi Again

If your car earth wiring is like the ( or at least my) +2S 130 then there are 3 earth points rear for the battery, the cock pit ( by which I think I call the dashboard ) and the engine block. You refer to a lot of measurments of voltage but to which earth do you connect the -ve side of the volt meter?

To eliminate an intermittant earth fault as the problem use the meter to measure the voltage drop between the 3 earths. So string your meter from say the dash earth to the battery earth, may need an extension wire on the meter then if on trying to start you see any voltage above 1V then a poor earth. Repeat this test for the other two possible combinations of earth. i.e dash to block and block to battery. Also check both the battery lugs both +ve and -ve to the actual terminal again anything above 0.1V suggest poor contact. picture attached shows what I mean

Hope this helps best of luck Bob
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