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Discussion Starter · #1 ·
I’m in the process of working on the electrical system of my 1970 1800e, exorcizing Lucas-inspired gremlin damage, the work-arounds of any number of nit-wits, the ministrations of the well-intentioned yet abysmally ill-informed, and I’ve come across a New Problem.

I cleaned the ground connection for the voltage regulator and did wire tracing and research on the cluster [email protected]#! of wires that are attached to the positive battery terminal. Previously I successfully swapped-out the fuseblock, and in this instance I didn’t go under the dashboard at all. There were more ‘mystery wires’ that were cut and dangling or terminals connected to... nothing –some of which can be figured out with the schematic– and the rest I do gentle wiggling and such to determine where they lead, etc.

Cleaned the ground, sandpapered-off corrosion, used electrical contact cleaner, and anti-corrosive zinc paste. The ALT light is glowing and I’m systematically tracking down problems as the alternator is keeping the battery charged BUT something is amiss, and the 40+ year old wiring is suspect. Anyway, as usual I test started and test drove... all ok... but then neither the oil temperature or water temperature gauges work. Then the next day w/o any particular prodding, the oil temp seems to be marginally ok, BUT the water temp gauge is doing an interesting impression of a voltmeter/tachometer, i.e. swinging into what would be overheat territory when the engine revs, and falling down to the lower ranges as the revs even out for normal driving. Interesting, entertaining, and disconcerting at the same time.

The fuel gauge is not showing any variability, so the voltage stabilizer may not be involved BUT I hasten to add I am not an auto electrician; I just play one on weekends. I replaced the wires to the sensors a couple of weeks ago, and the gauges had been working well prior to this. Dashboard lights or the operation of any other 12v electrical equipment don’t seem to have any effect. I haven’t gone under the dashboard to check the wires going through the firewall, as the connector in the engine bay checked out OK, through the firewall is where I’m headed next.

Before going further: I have a few auto electric books that are now well-read, have several technical articles from Swedish Embassy (thank you Ron Kwass!), increasing experience with a multi-meter, and several wiring diagrams including two that are colorized i.e. the green wire IS green on the schematic instead of just a black line and a note that says, “this one is green!” plus I’ll be installing Extreme wire to remove that as a potential source of interference!

Any ideas to help me use just one instead of several weekends to resolve this? I’d like to get back to that annoying ALT glow asap.
 

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Discussion Starter · #4 ·
Thanks for the replies, I had already gotten the basic black-ink schematics, and opted for the color coded ones. That helped immensely BUT as I dig in further it is obvious I have two things to contend with.

1) where the physical wire IS is'nt necessarily how it is depicted on the schematic, mostly close but not always.

2) cluster-F 'work' by previous sadists mean I have to bring it back to stock before the schematic helps as much as it can. As an example, the panel dimmer switch never was particularly functional, and I decided that actually taking good look at it was appropriate... upon inspection I believe it started off life as the volume control on a 70's HiFi system. It was wired into the system in a peculiar and interesting way, and I decided to eliminate it. Switch removal... did not affect the panel lights at all; they still do go on and off with the headlight switch though, which is a happy thing but... sigh.

I got a 12v wire tracker/tracer and will be hunting down 'mystery wires' and 'fixes' to undo as I gain more experience with the new diagnostic toy.

BTW, if there is any interest or if it might be helpful (or humorous) to others I can post 'highlight pics of of these electrical misadventures.

Brian
 

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Discussion Starter · #5 ·
... a small step for (a) man...

Quick update on the bizarre water temp gauge behavior.

Apparently the resident gremlins had taken advantage of a loose connector on the water temp sensor, and with the acquisition of a much brighter work-light I was able to reconnect one of my 'mystery wires' -after a suitable tightening of the connector, cleaning the terminal & connector, and the application of ACZP- and the gauge is behaving itself nicely now.

Of course that still means I have some stray grounding currents, but that is for another day!
 

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Discussion Starter · #6 ·
new gremlin

An update & maybe helpful info.

The 1800e courtesy lights have had some intermittent problems, and since I'm waiting for some parts I decided to do what I could to troubleshoot that system... couldn't be that difficult or confusing, right?

So, I started by replacing the old bulbs with new ones... that stayed ON no matter what the door switch, underdash light switch, or headlamp switch position was. :mad: Took the bulbs out to save battery, and over the next few days :facepalm: puzzled through various combinations of 'solutions' including taking an interior light housing fixture to see if anything was amiss there. Previously I used contact cleaner spray on the door switches, but the problem seemed focused @ the light housing somehow. While going through that I decided to clean things up both electrically and aesthetically and stumbled on an interesting phenomenon that I wonder is unique to me or a 'feature' of the 1800 in general.

When the cover is removed, the light is 'hot' and goes on; then when the cover is replaced it goes off and behaves itself as if nothing had ever been there. Problem apparently solved -save for a minor repeat that 'fixed itself'.

Other components are going to be replaced soon which require undercar work and clearance, but I found a rather clever item @ Pep Boys (no affiliation) that seems to solve a couple of problems at once. It's called a Unijack and it is a combination bottle jack/jackstand that both will lift a car @ the jacking points and lock it safely in place. You'll still need a floor (or other) jack to raise it to it's starting position but this seems an ideal solution I wanted to pass along. I got the 4000 lb ones, and I'll report back how well they worked.
 

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Yes, the courtesy lights are "hot" all the time, and the plastic lens interrupts the ground side of the circuit. It is a feature -- the idea is that you can pull the rear of the lens one click away from the housing to turn each light on when you're reaching around in the back seat without having to go around to where you can reach the switch under the dash. Usually, the lenses are brittle enough after all these years that they tend to break if you use them as switches.

You can also supply ground to the lights from the under dash switch in one position, or through the door contacts with the switch in a different position. You can defeat the door contacts in a third position, but the switch does not affect the lens function.

You probably know all that by now -- just explaining how it's supposed to work for others who might read this thread.
 

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Discussion Starter · #8 ·
Thanks Phil! it did seem to be a deliberate feature, and I did not know the details! The actual 'how it's supposed to work' is new information that may have taken me YEARS to come up with on my own!
 

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Discussion Starter · #10 ·
New Q:

In the process of cleaning electrical connections, I broke a tab off the cover for the TPS (Throttle Position Sensor). It was able to be reattatched BUT engine vibration knocked it loose and although the switch is still functional eventually the grit will wear it out.
SO: is there a low-cost functional TPS that will fit?
 
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