'79 Speedo not working
 

Well since I bought the car, the speedometer has not worked. I have just been using a GPS for reference. I decided to take the winter months to figure this one out. After doing some research on a few websites and forums, I found out that the issues can be with with the sending unit, corroded connection in the spare tire compartment, cruise control, or printed circuit board. My speedometer, odometer, and cruise control do not work. I decided to start with the sending unit. Directions I found said to use and ohm meter and rotate one of the the tires and it should open and close a few times a revolution. I hooked up my meter and found it to be working. Thought I would post a picture for reference and I post follow ups as I work my way through the problem.

http://forums.pelicanparts.com/uploa...1294720170.jpg

Next I am going to test the terminal connection at the CE panel to see if I have a signal that far and work from there. Supposed to be terminal T1 and T2. I'll post back my findings.

Let me know if anyone has additional suggestions.

Check the printed circuit board.....95% sure your problem is with the board

Ok, finished checking at the CE panel and it looks good up to this point. Gary, looks like I will be checking the circuit board....

http://forums.pelicanparts.com/uploa...1294806670.jpg

It's definitely the board. I found several terminal screws totally backed out on mine from a local shop that fixed the lighting for the PO. Ran them in, all gauges work great. Hopefully you'll be as lucky.

my board had a hairline crack in it. When I was driving I could reach under the dash and touch parts that made it start working again

Good methodology. thanks.

Sounds like the connector on my ignition switch. I can reach under and wiggle it making the stereo shut off. Need to pull and tighten/compress the terminals.

Mal replace the ignition switch,
or you might just let the smoke out of your ignition harness

But it only affects the stereo. I csn induce the gripe by wiggling the connector.

poor connection = resistance = heat = smoke= fire :)

Haha

Oh, you fear mongerers!! :D

When I bought my car half the electrical stuff didn't work. The more I drove it the more stuff started to work. So I do the same thing.. that was our legal disclaimer, besides that's what fuses are for.

Yep, they've got to wake up, and WD-40 helps this process.

Update
 

Finally got the gage pod removed (not too bad of a job) and it revealed some interesting things. The first thing I noticed was that a connector was kind of dangling from the pod, although still hooked up to the circuit board (Wow). It looks like the plastic broke and they tried to use a piece of an old computer circuit board for a cheap fix. This is the speedometer connector and turn signal light connector which are both not working. It is interesting to note that the speedometer is the last connection on one end and the turn signal is the last connection on the other end. The copper connections do not seem to have a good support under them (lousy circuit board fix) to make a good connection so I am hoping that this is all that the problem is. Also found a soldered in wire, but it works just fine. I don't have any other issues that I know of, but I plan on just doing some continuity and light bulb testing anyway. Do I have to buy the bulbs somewhere special or just at any car parts store??

http://forums.pelicanparts.com/uploa...1295492596.jpg

http://forums.pelicanparts.com/uploa...1295492634.jpg

http://forums.pelicanparts.com/uploa...1295492666.jpg

http://forums.pelicanparts.com/uploa...1295492709.jpg

Ohhhh, that looks familiar! I'm glad you found what looks to be the problem. I will offer you another piece of advice. Buy a new printed circuit board from 928 INTL for ~100.00 clams.

My reasoning (short story version): You are going to remove the cluster, clean everything up, check continuity (it will pass, believe me), re-install it and the speedo probably still won't work :o. Then, you will repeat this same order of operations many times (I did this as well as new soldering for a couple of weeks straight to "fix" my speedo problem). this thing will defy all laws of electricity. I even had my cluster bench tested by someone that I deem an electronic whiz (PhD EE); he even stated it should work; it didn't :( . I bought new speedo's and tach's; they didn't work either. By this time I invested so much time and money into this cluster problem I had to solve it. My wife thought I was nuts.
All hope was restored when I found someone selling an '83 cluster on the internet (not eBay). I bought it, installed it and happy, happy, joy, joy! :D:D:D:D
The Porsche paper circuit board is one of the worst damn inventions I have ever seen in my life:mad:. Make your life easier and spend the money for a new board.

He needs more than a new circuit board. The plastic housing should have extensions that the circuit board folds over and there should be a black plastic piece on each connection that locks the connection together. I will try to post a photo or 2 later today showing details...one of the black plastic retainers can be seen on the laast photo, all 3 connectors should have these, otherwise, many problems...

and you are very correct, this is a very poor method to connect electrical devices...starts out OK but over time and repeated disconnects/reconnects the stuff ages and becomes brittle and fails....

Someone has already put a new board in it once. The original ones were brown.(not sayin you don't need a new another new one) The tabs must be a common failure, Mine looks exactly the same. I've had the tabs "hangin" for 20 years. When I put a new board in I couldn't find a new back to the cluster. So I just had to roll with it. Still working ok.

Yeah, I'm looking at the photos and you are correct! He is missing the connectors. Good call!! How's your resto going??

I have cannabalized three instrument clusters so if he needs any parts he can post here or PM me and we exchange info.

One thing to keep in mind, I believe that starting with MY '83 the clusters moved from 12 pin connectors to 14 pin connectors so the clusters are somewhat year dependent. I have both a very poor '81 with broken off plastic guide parts as well as a very good '84 that I got from Mark Benton for a very reasonable amount of $$. I think '82 back to '78 are generally pretty much interchangeable, at least as far as all the major functions go. I understand some 5 speed cars have a shift warning light(?) and Euros may also differ? My '81 was a 5 speed and all the others have been autos so what I know for certain is very limited...like maybe the sun will rise tomorrow, all else is speculation on my part...

Regards my resto efforts, one car scrapped, one car on the road running well and sold, and the 3rd car is licensed and inspected, but currently have a leak in the vac line to the transmission so it is up on stands awaiting dropping the exhaust and heat shields to find said disconnect.

PO's mechanic really did some crap work.....bad rear wheel bearing now replaced, axle nut on bad WB was finger tight, as was new starter mounting bolts, flex plate to drive shaft coupling was torqued to about 5 '#'s, all lug nuts were finger tight, 2 directional tires were running the wrong direction, the Boden tube retainer was on the wrong side of the bracket, the kickdown cable was entirely hosed leading to no more than 1/3rd throttle possible.etc...etc....

The good news, I have the gremlins out of the cluster, the interior of the transmission looks like it is all new, the engine runs very solid, it has a new TT, new alternator (also with finger tight bolts), very clean, new dual exhausts with Holley glass packs (loud) etc etc...the interior has cleaned up great, with a few interior parts from Mark Benton as well as fellow Pelican listers as well as some from Renn.....as I recall I got the dash and pod from you Gary did I not? Thanks on that one, big time....a big help to me!

http://forums.pelicanparts.com/uploa...1295541785.jpg
http://forums.pelicanparts.com/uploa...1295541826.jpg
http://forums.pelicanparts.com/uploa...1295541855.jpg

More work to do, but I am generally pleased with the progress...sorry about the thread drift....

Is that the dash I sold you this summer in the car above? What a world of difference. Who did the re-leather?

Great job & nice work!

-Sorry for the thread hijack-

Yes, that would be the dash. (check out my post #20) But I used one of the plastic covers on it after stripping off the last leather covering. Did you realize it already had 2 leather coverings on it? By the way, I suspect the plastic is a mistake given the summer temps in Texas, but I wanted to get the car on the road and make certain it was worth the cost of a proper dash covering ultimately. Not there yet, like many of these, many things yet to resolve, the autobox (NOS) shifts very hard (like no vac) so I am now considering options for that.....

Is there any way to test the speedometer before I get all this back together? I would hate to do all this work only to find out it doesn't work.....

Found an interesting un-used circuit for "Turn signal (trailer)" while testing the circuits on the board......anyone have this as an option?????

You could do a solid wire conversion as I did... messy and time consuming but effective, cheap, and much easier to repair.

http://forums.pelicanparts.com/uploa...1296343711.jpg

Looks good.


Leather dashes are regular vinyl-covered dashes that are covered in leather. Yours had plastic, leather and leather?

I hate when you post this.. it makes me feels totally inadequate.:) nice work, I'm jealous

I came across another person who had done this and was strongly considering it. I was even looking around for the connectors. Where did you get them?? What gauge wire did you use?

Same fried wire
 

I have the same fried line on my 80 euro printed circuit. It goes to masse (ground) on the lower right connector. If the connector positions were as follows when looking from driver seat at bottom right pod connector:
IXIIXIIIIIII in the 2nd and 5th position brown wires and the 2nd position goes up the printed circuit card from MASSE and burned in half on Circuit.

I have replaced my printed circuit but do not want to fry the line again. Can anyone please help? I noticed the dash light potentiometer double blue / black wires were on the high side and the black wire was closest to the mount, which appears backwards of all pics I see. I have since reversed this since the 1st burned line.

There is also a push button just to the right of the dash light potentiometer, reset odo I think. How are those wires supposed to connect please.

I believe you are describing the push button is for the intensive washer if wires are blk/vi and blk; blk goes to the 15 side if labeled.

Thank you for responding. Hi, I have two black push buttons and two potentiometers.

Left Side is dash dimmer, then there is a button just next. That is the one I am referring to. I think that one is the trip reset. I will certainly check 15 and verify black is going there.

Right Side of steering wheel under pod, I have wiper frequency pot and another black push button. Is that one the pot for intensive washer?

What was awful is that I had full lights and guages for 10 secs, then the sizzle on the same pic on page one of this thread.

Chris, sorry I overlooked your question.....it appeared to be 2 layers of leather over plastic...I peeled off the top layer of leather. the under layer was much thinner than the top layer, but it was nicely glued down and tight in most places and only required a bit of dressing down the corners to get the cover to fit. I did not pay a great deal of attention to the construction. I know I will regret the plastic cover later, but for now the car looks presentable at about 10% of the cost of doing it "right". If or when I take off the plastic cover I will pay more attention to what is left under it...and if it is truely plastic or leather....whatever it is, it was different than my other '84 and '81 dashes...

Sorry, I ref'd the right switch for stated wires. In the Owners Manual there is no button on the under left to the right of the POD illumination control. I had a toggle (SPST) switch where you indicate and could not trace it to anything it is still there...i'll probably turn it into a cutoff switch??

Third down on left face of the POD is mileage reset.

Thanks JhwShark. Do you know how the left light dimming switch is to be wired for the Blue / Blk wires and the black wire? I will include a pic of my left pod switch on the 80 Euro.

jtapps...we don't want to hijack a thread

Please start a new thread with your subject and the pic's so we can help.

Alright, will do. Thanks

open circuit
 

Ok, think I found some of the problem. There does not seem to be continuity through the rivets to the posts that go into the speedometer. Seems to be a solid circuit board riveted to the flex board. Out of the four, one is not used, one receives the pulse from the sensor, one is power and one is ground. So far the ground and power have no continuity back to the connectors. I'm thinking there are issues with the rivets. Also, looks like someone was in here before to replace the motor and a resistor. I did move the motor and the odometers spins, so no broken gear. Can I just solder these?

http://forums.pelicanparts.com/uploa...1297656590.jpg


http://forums.pelicanparts.com/uploa...1297656628.jpg

update
 

I have now soldered the rivets and have good continuity from the pins that go through to the speedometer to the plugs. I soldered both sides of the rivet, since I found I still had problems on the top side.
http://forums.pelicanparts.com/uploa...1298255490.jpg

http://forums.pelicanparts.com/uploa...1298255529.jpg

http://forums.pelicanparts.com/uploa...1298255563.jpg

This is just one of the issues I found so far.

Forgot to mention that the long posts appear to have been soldered by someone before me