I replaced my '85 300D's ignition electrical switch, steering lock and keyswitch on the weekend... then had issues re-installing the gauge cluster... outlined in this thread: Broke multi-pin instrument cluster connector - cluster now messed up - w123

After I thought I had the cluster back in and everything was okay, I had a range of issues for a few hours:

- seatbelt warning light would randomly illuminate for about 10 secs at a time.

- fuel and temp gauges would either flutter wildly or peg at max for 5-30 seconds, usually after hitting a bump. (The seatbelt light and the gauge fluctuation did not occur at the same time.)

These weirdnesses continued for about three hours them stopped. Everything seemed fine for the remainder of the day.

Then this morning I went to leave for work and I had no preglow (but the light came on).

QUESTIONS:

Any ideas on what I did to cause yesterday's symptoms? Though they have stopped I don't consider that 'fixed'.

Is there any way that the events of yesterday are connected to the preglow issue? I am thinking it's a fluke of timing (sudden failure of relay).

Thanks

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Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

I skimmed your other post (website acting up). It sounds like you tried several different clockings of the round dash connector since the key broke off. That could have connected who knows what to each circuit and to the components throught the car. That key broke on one of my 300D's, so I figured out which color wire should go to which pin and marked the board and connector w/ a Sharpie. I can't fault you since I often do something dumb when pressed to fix a car. More so when I was younger. You learn that being methodical wins in the long run.

Did you connect the ground to the back of the cluster and make sure it is connected to the ground point behind the cluster? Bad grounds are common problem.

Interesting - this guy had similar problem, but didn't post his cure.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

Pardon the dumb question, but which is the ground? EDIT: Found the answer in the BW link you provided.

As far as I know, everything is now plugged in that was plugged in when I pulled the cluster.

Evidence is starting to point to something not plugged in securely, however... the gauge problem came back on my drive home and it's a factor of hitting bumps. The connector must still be loose.

And the ground is in the round connector... booyeah.

The advice in the BW thread about adding a ground triggered a memory that old Volvos had a similar problem (and fix).

The glow behaviour is going to be another issue, I suspect, as it's acting up independent of the light working or not.

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Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

There is another ground wire on my car. It connects to the back of the cluster and from there runs to the firewall. Maybe I added it? It is usually a pain, so many owners (including me) installed a spade connector part way to make it easier to remove.

The other possibility, is that the ground trace on the circuit board got fried. It's not hard to do if the battery is connected while you are R&Ring the cluster.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

Where is it located? (Behind what part of the cluster?)

I have the cluster out of an '84 as well and don't see an extra connection.

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Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

I can't tell you exactly from memory. I checked all my pics and couldn't find it there either. But I do recall it comes off one of the screws that joins the right side of the cluster (looking at it from drivers seat) to the centre speedo part. There are ground traces behind most of those bolts and the metal back of the cluster is at ground.

It is a common "upgrade" to add a cluster ground. If you look at your 84 cliuster, you should be able to pick which screw to use. I have a ring connector on cluster and then a spade 1/2 way to firewall.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5