Lotus Elan and Lotus Elan Plus 2 Forums

Hello All,
Me again - didn't want that last electrical problems post to get too long, so I separated out the ignition troubles here.

Here's the issue. Out driving in March the first few weeks I had the car. Car # 7002040030K. Driving along at about 60, engine died, tach immediately went to zero. A couple seconds later it started back up again, and I kept driving. About 5 minutes later, engine died, tach to zero, didn't recover, pulled over, wouldn't start again, called the tow truck. At home I discovered I had no ignition power in the white wire to the coil. With the wiring diagram and help from you on this forum, I checked the anti theft switch. No power there either. Spent a day or two trying to get to the back of the tach to check the connection there, but gave up and went back to working on other cars. I ran a jumper from the fuse block to the coil and have been driving it that way since.

So yesterday, I started troubleshooting the iginition problem again. I have the wiring diagram and my test light, trying to sort out the problem. Pulled the ignition switch out of the back of the mounting. Only 7 wires instead of 9 shown in the wiring diagram. No radio in my car, so the green wire from terminal #4 is missing. That's the easy one.

Terminal #1. Supposed to be one brown with blue stripe power wire and two brown feeder wires to other locations. I only have one brown wire, so either the window switches or the hazard flasher are not getting power. Not sure which, neither are working.

Terminal #2. Supposed to be 3 white wires, one to the ignition warning light in the tach, one to the tach/anti theft switch/coil, and one to the "green wires" fuse. I have 3 wires, but one green one goes to the aftermarket fuel pump, there's one original looking white one, and one home made red one. Since the fuse wire, ignition wire, ignition warning light, and fuel pump were all working at one point, I had 4 things working off of 3 wires. I found a white wire loose in the vicinity of the ignition switch, thinking it could be the ignition wire that had gotten disconnected (but then it would have had to work itself out of the bundle, no chance), but believe it or not it's hot all the time when the battery is connected, so not sure where it's power is coming from. So at this point I'm not sure whether it is the white wire or the red wire powering the ignition warning light and the "green wires" fuse, or which one used to power the tach/ignition circuit. More work required there.

Terminal #3 One white with red stripe wire to the starter solenoid. As designed, working fine.

Terminal #4 White with purple wire feeding the "purple wire" fuse. Green wire to a radio is missing.

As I said in my other post, I'm considering buying a new wiring harness and connecting it all up correctly, thinking that might be easier than trying to run down all these incorrect wires, connections, loose wires, taped splices, etc. Any opinions?

Any ideas on that ignition wire that suddenly lost power? I still have to pull out the driver's seat, get on my back and see if I can get to the back of the tachometer to make sure it's connected there.

Thanks in advance for your help and advice.

Cheers,
Rick
70 S4 Elan convertible

I'll keep plugging away, trying to identify which wire's going where until I hopefully sort things out.

I might have missed it in your question.
How is the White wire on the back of the tachometer. Use a large alligator clip, to be sure it has contact.

just in case : I had a similar issue when initially getting my car back on the road : it was the fuse holder (springy brass 2 prong spring inside the fuse box) not pressing enough when getting hot.

Thanks so far. I'm off on a little British car hunt this morning, so I'll get to those ideas tomorrow. I'm not quite sure I'll get my hands up to the back of the tach yet, but when I get the seat out and lay on my back, perhaps I'll see a way to get an alligator clip up there.
Cheers,
Rick
70 Elan S4 Convertible

It helps to remove the large phillips screws holding the dash in place as well as the two holding the steering column
clamp. This will give you just enough room to get your hand up behind the dash to your tach. Also, you mentioned a hot white wire back there. Has your tach been converted to RVC due to the installation of electronic ignition? If it has, it might leave a spare hot white and you'll have a new wire running from the sensor wire on the tach to the negative side of the coil.

+1 on sliding the dash out and saving the footwell acrobatics and bad back !

...lean the top of the dash forward so you can see the tacho in daylight it's much easier and you get a proper look along the top at all the other wiring.

If you don't want to do that, if you can disconnect the speedo and remove it then you can get better access to the rear of the tach - I'm not sure what you'll find in there but good luck

Iain

Lots of good information, thanks. I did discover late Friday evening that I do indeed have a Pertronix module in my distributor, but I'm not sure what my tachometer converted to RVC means. I'll work on getting the dash loose and getting to the back of the tach to sort that out today or tomorrow. Still, the hot white wire hanging down by the ignition switch is confusing because it is hot with the switch turned off, but hopefully I'll be able to sort that out when I get the dash leaned out and I can see the back of the tach.
Cheers,
Rick
70 Elan S4 Convertible

Rick,

To get your tach to work with the Pertronix it’s likely been converted from RVI to RVC.

The Spidya kit is often fitted inside the tach to convert it to RVC, this changes the wiring as it doesn’t need the impulse sensing of the original RVI tach, it gets its signal direct from the coil.

You’ll need to download the Pertronix fitting instructions to help you understand what the wiring requirement is so you can compare with what you have.

Iain

Hi Iain,
Well, the tachometer was working with the Pertronix when I got the car. The tach died at the same instant that the ignition quit, and now that I have a jumper wire from the fuse box to the coil to start and run the car, of course the tach doesn't work. What that tells me is whatever was needed to be done to make the tach work with the Pertronix has been done. I'll just have to get to the back of the tach to see what wiring is back there now to see why my ignition wire quit working.
Cheers,
Rick
70 Elan S4 Convertible

Rick, this is how your ignition switch should be wired:


When the Petronix was added your tacho could have been converted from RVI to RVC, in which case, instead of the white ignition wire being fed through the tacho, you could have a seperate wire from the coil to the tacho.

If it ain't broke don't fix it!

If you reach behind the dash, there are a couple of nuts that hold the tach in place, remove them and the tach comes out the front of the dash. It is likely that the white wire going from ignition to tach to security switch to coil has come loose. Dan

Thanks all,
Frustrating day. Haven't gotten to the back of the tach yet. I'm digging quite a deep hole so far.

1. Started out trying to move the dash to see the backside of the tach. Got all 6 of the big screws out and the two on the steering column clamp. Dash pulls rearward a couple of inches. I can lift up the plastic dash cap an inch or so and can see the top of the tach, but not the back. Something is keeping the dash from either tilting to the 60 deg position someone (or the manual) mentioned. Might be the heater control knob. Might be the bottom where the dash sits on the transmission tunnel. Gave up and moved to #2.

2. Next, I removed the driver's seat and got on my back to see if I could get to the tach. Even with that black molding that screws to the bottom of the dash removed, I still can't see nor can I get a hand to the back of the tach. I do see a bullet connector and a couple of more white wires in the ignition wiring which explains why all three aren't connected on the ignition switch like the wiring diagram shows. There's another loose white wire back there, maybe that's the one that has come out of the back of the tach. On to #3.

3. While I was under there, I decided to go for option #3, which is to remove the speedo so I can see the tach from the side. Got the knurled nuts with 6 ground wires and the side clamps off. Couldn't get the reset knob to come loose, so came inside to read about how to do that. Read about the tiny pin, but then saw a post that removing the voltage regulator would be easiser. Still, with that off the back, the steering column will still be in the way. Do I need to remove the clamp down by the pedals that's holding the steering column up to move it out of the way to pull out the speedo? It would be nice for the workshop manual to give us that kind of information.

4. Now I see the note from Phil about my tach already being converted to RVC since it was working when I got the car and it already had a Pertronix in it. So if that's the case, then there's a separate wire from the coil back to the tach, Then, no need to try to follow the white wire to the tach, it must be disconnected somewhere else, but I don't have any idea where else to look. Since there was no power at the white wire at the anti-theft switch, previous owner must have not connected it either when he switched to electronic ignition. There is that spare red wire from the ignition switch to the vicinity of the coil. I could hook it up to the coil and see if it will start the car, and once it's started, the tach ought to work. But now everything is disassembled. I'll have to reassemble quite a bit to give that a try.

Tomorrow is another day!
Cheers,
Rick

One more thought. But why doesn't the tach work when I run a jumper wire from the fuse box to the coil to start and run the engine. That's essesntially the same thing as using the red wire from the ignition switch and hooking it up to the coil. If the tach has a separate wire running from the coil back to it, it should work when I run a different wire to the coil. I guess that means I need to keep trying to get to the back of the tach after all. Food for thought for the evening.
Cheers,
Rick

No need to remove the speedo reset knob, believe it or not, to remove the speedometer. With the right
'angling', it'll come out.

Hello All,
Wow, seems like forever since I posted last. Major progress in these last two days, although still haven't solved the mystery.

1. Finally this morning I removed the bracket holding the steering column up by the pedals, and was able to move it out of the way and access the back of the tach. I removed it only to find that even though I have a Pertronix in the distributor, my tach has NOT been converted from RVI to RVC. The two white wires were stilll there. Believe it or not, I had continuity from the ignition switch to each wire in and out of the tach. Dumbfounded, I checked the white wire at the coil, and had continuity there too. Not believing my eyes, I hooked up a battery charger to the ignition wire at the switch, and I had test light power to each wire in and out of the tack and at the coil.

Does that mean that my problem is intermittent, and it's inside the tach? Is it because the tach hasn't been converted to RVC?

2. I put enough things back together to try to start the engine again, and sure enough, it started with the original white wire that runs through the tach and the anti theft switch to the coil. The tach did read intermittently, though. Back to square 1. I talked it over with a friend in town who's particularly good with electrical issues, and he said to test the tach I could run a parallel wire to the coil. I told him I could do better than that - I had already found a parallel wire from the ignitoin switch to the coil, all I had to do was hook it up. So now I have the original white wire routed as it was originally, and a second wire directly from the switch to the coil.

3. Before I put everything back together to go for a drive and see if the tach acts up again, I figured I ought to try to fix some of the other electrical issues I have. But first I went through checking and removing as many of the previous owner added, unused wires as I could identify. Believe it or not, I removed 6 wires, 4 of them that ran from behind the dash all the way to the front of the car - 3 of them were black - one attached to the earth bobbin in the engine compartment, all the others not connected on either end. I don't know what he must have been thinking? Maybe they were all attempts to get the headlights or the horns to work (headlights still don't, and the horns are missing). But that's for another day.

4. Can anyone tell me what this little box is I found attached to the back of the dash below the tach? It looks to have a brown with blue power wire to it, and two green with brown stripe wires leaving it. I don't see that anywhere on the wiring diagram.

5. More on the positive side - I found a double bullet connector in the white wire leaving the ignition switch that splits into 3 white wires - just not shown correctly on the WSM wiring diagram. Also, the white wire dangling by the ignition switch that had power to it with the switch off was connected to a bullet connector for the brown with blue power wire feeding the ignition switch. I pulled that out to keep it from causing mayhem.

Still many more electrical things to sort out, but I'm making very good progress - thanks to all of you - but especially Phil Harrison who's been sending me pictures, color coded wiring diagrams, texting, and phoning to help me sort this stuff out. He scared me away from a new wiring harness as nobody makes/sells one that works for the Federal spec S4 cars, unfortunately my car. I'll just have to persevere with what I have.

Cheers,
Rick