89FrontPorsche

Well, I read all there is to read thread-wise about the instruments not working...but this one is a unique and unusual deal for me. The last time the instruments stopped working, it was fuse #24 that had blown because of the interior lights snafu. New fuse 24, keep the light connections away from the body of the car and I had instruments.

Except a water temp gauge. It quit working a few months after I got the car. The overheat light and the fans work just fine, cycling on/off as they do. But today, since I was repairing the cruise control stalk while I awaited a replacement four-prong control package from Phoenix, I decided that since the instrument pod was easier to get to, might as well clean the electrical contacts to the circuit boards that the cluster uses.

OK...so....took it all apart carefully, cleaned every single contact. The pins that plug into the connector for the instruments, the metal sticky-outie things (that would be the technical term) on the back of the cluster that slide through the metal connectors where the light bulbs all go into and so on. Also took the circuit boards out and examined them with powerful glasses to see if there were any connections that were bad or cold solder joints. Found a couple on some big resistors and re-soldered them.

That's when the fun began. Fun being the term I use rather than the cussing and throwing things. Because, when I first put it all back together and started the car, the computer displays worked, the instruments all worked but I waited and waited for the temp needle to move and....no action there.

So, I disconnected it all again and re-examined it all. Nothing out of the ordinary for a 23 year old circuit board. But when I plugged it all together again....I got....bupkiss. Nada. The only thing that works is the ammeter. The oil pressure gauge "works" but goes to the peg 3 seconds after the key is turned on, regardless if the engine is running or not. The daytime backligthing works as well. But removing and re-installing all the blade connectors resulted in the warning lights all working as required one time. Still no tach, no computer displays, and the only other difference was the fuel gauge reading a quarter of a tank. There's actually 3/4 of a tank of gas right now.

I fear that the circuit boards couldn't take the strain of being looked at. I checked and re-checked fuse #24. I am going to take the fuse board out tomorrow and examine the connection for that fuse from behind but...honestly, I didn't do anything to the fuse until the instruments didn't work when I re-connected the cluster.

I have no desire to pay for a new circuit board, especially if I install it and find it doesn't remedy the situation. It was working A-OK until I cleaned the contacts, except for the temp gauge. Now it's pretty much dead.

Kinda hard to enjoy the car without the full compliment of gauges, etc. Is there another fuse to look at? #10 says "Instruments" but I checked it and it's fine. I think the problem is more complicated than just a fuse this time and I probably damaged something. No banging around...no overly aggressive cleaning on the contacts...nothing like that. I know better. I wonder if re-soldering one of the big rectifiers on the secondary board has caused the problem. I do not know how to check a rectifier. However, if they're available at the right rating, I'll replace it. Not that I'm cheap...I just think replacing a whole circuit board for a single bad component is ridiculous.

But, for those of you who have been patient enough to wade through all this, if you have any ideas, I'd be glad to hear them. I spent seven hours examining, looking, even getting a meter out and seeing where the board has power and where it doesn't. Wasn't very successful with that.

In any case, I'm at that point somewhere between crying a river and pushing the car off a cliff, which I know I'd regret. But electrical problems are only easy once you discover the problem. Finding it is downright maddening.

So this is my call for help.


Thanks guys.


89FP

ROG100

Call me tomorrow as I have a number of early CB's we can try to see if they remedy the situation.

89FrontPorsche

Thanks Roger,

I left you a message earlier this evening, yes that was me....whining and crying. LOL

I'm working but I'll try to ring you up sometime during the day.

Cheers

89FP

jeff spahn

At least you aren't in the order per day club with Roger like me. "Hi Roger, can you overnight me an XXXX?" See you tomorrow.

blown 87

I have a few that call me by name when they pick up the phone.

ROG100

Jeff - we laugh and cry with you every day - coming to an end very soon.

Mrmerlin

before you do more i would retrace your steps,
you may have unwittingly cleaned the connectors too well. .
remove the connectors and examine them with a magnifying glass see if any of the connectors have the connectors spread apart,
if they are then you may have found the issue.
I would also hope that you have the 4 connectors on the correct mounting tabs

Bill Ball

+1

Also, when a gauge doesn't work, the contact posts often need resoldering at the gauge end.

Hilton

Its worth pointing out that digital clusters from any year can be used in an '89 - in case you start looking for a replacement used cluster.

89FrontPorsche

Not sure what you mean by this. Not sure how the "connectors would spread apart". I'm not trying to be difficult, nor do I have problems with English. I'm sure you know exactly what you mean. But, it's like, "Hold it up to the phone, so I can see what you're talking about". More clarification, sir, if you please. You've been brilliantly helpful to me in the past.

By the "four connectors", I believe you mean the four "levered" connectors on the back that slide onto the boards. On my car, they won't go on in any way other than the way they were intended. By that I mean, on the correct Left/Right orientation and on the correct board. The connectors are designed in such a way that I cannot hook them up on the wrong board (ie: front to rear or vice-versa). Unless there's something a Padawan like myself is acutely unaware of.

However, that said, Thanks very much all for helping here. I'm truly frustrated and as much as I love my old Ford Truck...I had to drive the old veteran to work this morning with the 250lb diesel Volvo marine engine in the back (it goes to the boat, of equally ancient vintage) at 16mpg, etc. No radio, 1 hour of boredom and pondering the electrical gremlin on the 928 the whole way.

89FrontPorsche

Quick posting to Thank Roger in TX for his help. The replacement circuit board is on its way and we'll see how/if that helps and I will report on any/all changes.

At this point it appears that a board is the only way to fix this.