84 4+3

I have been having an on again off again issue for the last couple of years with the digital dash. Basically, the trip and mpg readout on the dash will reset itself after sitting for a week or too. I've tested grounds and had the cluster apart and fixed all the cold solder joints. It's something that is annoying more than a problem if you will. I have also noticed it doesn't seem to matter if it is just sitting or if the car is on the battery tender for that time. It just wants to happen. I read through the fsm but it seems a little light on this section. Any help is much appreciated. Thank you in advance.

gerardvg

Hi Check your battery connections and ground connection from drivers side frame to above oil filter, and on the bell housing bolt there are a few ground wires there also. My 85 dash readout will only be lost when battery goes flat (even while cranking with a low battery charge) a bad connection will reset the trip and average mpg).

There is a ECM disconnect wire near the battery, check that connection is good also.

Good luck

84 4+3

Will do. Thank you.

WVZR-1

An '84 I believe has an unusual ground not used in the later (moved for reasons I'd think), that ground in an '84 would be G101 and on the right kick-panel/hinge post area. Easy reach? Maybe not -

In '85 I believe this ground was moved to the driver kick-panel and the zones were renumbered to an easier to follow pattern. It's G201 and there's images I've posted scattered throughout the C4 section, Cliff Harris has posted information also. Should be an easy search.

Am '84 FSM shows the ground in an image 8A-49 on maybe page 8A-56, maybe you create a similar ground position on the driver kick-panel area. If you don't have I can post an image for you.

84 4+3

I looked through my manual. I do not have a 8A section. I'm going to look for it now...

WVZR-1

You don't have the Electrical Supplement then I guess?

84 4+3

I would guess not. I cleaned up what I could find. Everything was tight and clean though so I don't know.

Bfenty

Sent you a PM.

84 4+3

After sitting since Sunday it has reset itself again... the plot thickens.

auto_cran

I was having the same issue with my newly acquired '84 where I would go out to start the car and the trip odometer and average mpg where reset to 0. I was also having issues when driving, the entire dash would flicker when going over hard bumps (worse when colder out).

I checked what gerardvg said - the ground wire connection that's above the oil filter. I couldn't believe how loose it was. Just for grins, I had my wife check the digital dash as I jiggled the wire - yep she saw the dash flcker.

It's been about 3 weeks and 100 miles since I cleaned and tighten that ground wire connection and I haven't seen the dash flicker once and my trip odometer and avg mpg hasn't reset automatically....

Chris

84 4+3

It felt tight from up top but it's just too cold out to slide under it. I'll check it in a few weeks when I do the oil. I've been busy with other things as well. I kind of figured it was a grounding issue of sorts anyway.

hcbph

Does the radio in your car reset if you disconnect the battery and does that happen when your gauges reset?
I have a battery cutoff on my 86 and when I use it the trip, miles recorder and radio has to be turned on and the presets are gone.
If yours does that then it appears it might be losing the electrical connection when the condition is happening.

Just a thought hope it helps.

84 4+3

So I think I inadvertently found my problem. A couple weeks ago I went to start the car and she was stone dead. Same thing a week later. I've done drain tests prior and only get about 15-25 miliamps of draw which seems reasonable to me. So I decided to load test the battery. It tested at less than 50% of it's new stated capacity. At only 3 years old I was nervous then remembered a conversation I had with another c4 owner. He said for whatever reason he kept having Bosch batteries fail around the 3 year mark and mine is also a Bosch. Maybe it is time I replaced it again.

At any rate I drove the car yesterday and confirmed the alternator was operating properly. This morning the battery is sitting around 12 volts so it is a little flat. If I used the car more if probably would be fine.