Cluster fault found and fixed and Defrost Pod sorted as well
09-12-2006, 09:02 PM
#1
Instructor
Thread Starter
Join Date: Nov 2005
Location: Wellington, New Zealand
Posts: 161
Likes: 0
Received 0 Likes
on
0 Posts
Cluster fault found and fixed and Defrost Pod sorted as well
This is a bit long but thought you might like to hear about these jobs.
Cluster
I have the digital cluster in my 89s4 and the temp and volt gauges have always been erratic, sometime work, sometimes don't etc, banging on the pod helped sometime as does wriggling the right hand connectors. I thought it might be tarnishing on the connectors so have already had it out and cleaned and reinstalled. The gauges worked perfectly, for about an hour. That was some months ago so I decided to have another go.
I used a short form cluster extraction technique combining some ideas i have seen on rennlist (thanks schocki). Basically:
Remove steering wheel
Remove parcel tray
Remove mouldings under column
Remove two pod hex bolts
Loosen indicator/cruise/wiper mechanism
Move pod forward and tilt over ignition switch
Wriggle the cluster free and remove connectors
Slide out the back of the pod and to the left (on my RHD car)
Total extraction about 20 minutes, all other pod switches and connections left in place.
Stripped the cluster down, ummed and ahhed a lot, resoldered the pots on the back of the gauges (saw on rennlist to do this but don't actually think it does anything)
Put it all back together and reinstalled to car enough that i could run the car and see if it was fixed. It was not. So:
Removed cluster
Disassembled again
Did some more head scratching and found...drum roll...
that the green multi pin connectors on the circuit board (which locate into the bulb board) are soldered to the face of the circuit board, rather than through the board as i might have expected. This means the pins lay flat in small dabs of solder and most of these pins had separated on the connector closest to the hinge. This would have occurred with the back of the cluster being opened to get access to the bulbs at some point in the past because this connector grips its mate quite tightly, particularly because of the lateral force put on it when the PCB swivels on its hinge to open. This means that pressure almost anywhere on the back of the cluster would increase connectivity even just from the torsion on the loom, so gauges might work a while but vibration and movement will separate the pins over time.
I resoldered carefully and after fixing up some stray solder that i had not been careful enough with, I reassembled, reinstalled and started the car and yes it looks like its all fixed. I now see that the stop lamp lights up on ignition each start (had been erratic as well) and the volts are sitting nice and steady at just shy of 14. After a test drive everything in the cluster ppears to work perfectly for the first time since I bought the car.
First moral of the story, when you open the back to replace bulbs check the green connector close to the hinge with a magnifying glass and if you already have gauge problems consider this as a possibility.
Second moral of the story, you do not need to remove the gauge needles. I know this because I thought I did, and though I carefully photographed needle position for reinstall I am out an annoying needle width on the temp and oil pressure gauges so I'll need to go back in to fix them, but might wait until I have a bulb to replace or something similar.
Defrost actuator
Months ago i did a full vacuum diagnosis and found the centre comb actuator was faulty along with the defrost actuator. I plugged these while i got around to fixing them. I was also thinking that the price for new actuators was a bit too porsche for my liking given that you only strip out the diaphragm from the new part to use into the old part so have been looking for other solutions or bargains. About three months ago i spotted a new old stock Mercedes vacuum pod on eBay for US$5 that looked like a good match though the actuator cap was pink!
Anyway last night after finishing the cluster reinstall I had a go at the defrost actuator and the short story is the Mercedes diaphragm is a perfect match and the actuator is now fixed, big grin as i watched the arm go up and down as I moved the heater control. All this with the dash and centre console in place. Here is the long form procedure if you are interested (all for a RHD S4 but would translate easily to a LHD car i think):
Remove parcel shelf
Optionally remove steering wheel (I did not but it would make it much easier if you are larger than medium sized)
lying on your back you should be able to see the base of the actuator and two of the four lugs that hold the cap on, get a screw driver onto those and work the cap off - this was fiddly and probably took 15 minutes just for that.
With a long slot end screwdriver reach up to where the actuator arm connects onto a plastic push pin on the flap arm and with the screw driver head between the plastic flap arm and the actuator arm twist and this should pop the arms apart.
Work the actuator arm down and then you will need to get out from under the dash and from the front to the left of the steering column there is a smallish gap between the column mouldings and the centre console, sort of a horizontal gap about 5 cms high and maybe 15 cm long. With a bit of fiddling you should be able to work the rubber diaphragm with arm attached out though that space. Once you have taken the old diaphragm off and put the new one on reinstallation is the reverse, i.e. feed the arm first into that gap by the steering column from the front (being careful not the split the diaphragm because it is a tight fit) and once that's in the actuator body go back under the dash and proceed from there.
Mostly its just plain tricky with such limited access and visibility. I used a head mounted light and that's probably the best option. To get the actuator arm onto the flap pin was perhaps the single hardest task, in the end i got two long extensions from my socket set and put one behind the flap arm and one on the other side of the actuator arm and just pressed them together. Very pleased to hear the click as that job took about 15 minutes as well. Total time for the replacement was about 45 -60 minutes.
I wish i could tell you the Mercedes part number but it came without one.
All in all, a pretty good two days and two annoying problems fixed for virtually no $.
Cluster
I have the digital cluster in my 89s4 and the temp and volt gauges have always been erratic, sometime work, sometimes don't etc, banging on the pod helped sometime as does wriggling the right hand connectors. I thought it might be tarnishing on the connectors so have already had it out and cleaned and reinstalled. The gauges worked perfectly, for about an hour. That was some months ago so I decided to have another go.
I used a short form cluster extraction technique combining some ideas i have seen on rennlist (thanks schocki). Basically:
Remove steering wheel
Remove parcel tray
Remove mouldings under column
Remove two pod hex bolts
Loosen indicator/cruise/wiper mechanism
Move pod forward and tilt over ignition switch
Wriggle the cluster free and remove connectors
Slide out the back of the pod and to the left (on my RHD car)
Total extraction about 20 minutes, all other pod switches and connections left in place.
Stripped the cluster down, ummed and ahhed a lot, resoldered the pots on the back of the gauges (saw on rennlist to do this but don't actually think it does anything)
Put it all back together and reinstalled to car enough that i could run the car and see if it was fixed. It was not. So:
Removed cluster
Disassembled again
Did some more head scratching and found...drum roll...
that the green multi pin connectors on the circuit board (which locate into the bulb board) are soldered to the face of the circuit board, rather than through the board as i might have expected. This means the pins lay flat in small dabs of solder and most of these pins had separated on the connector closest to the hinge. This would have occurred with the back of the cluster being opened to get access to the bulbs at some point in the past because this connector grips its mate quite tightly, particularly because of the lateral force put on it when the PCB swivels on its hinge to open. This means that pressure almost anywhere on the back of the cluster would increase connectivity even just from the torsion on the loom, so gauges might work a while but vibration and movement will separate the pins over time.
I resoldered carefully and after fixing up some stray solder that i had not been careful enough with, I reassembled, reinstalled and started the car and yes it looks like its all fixed. I now see that the stop lamp lights up on ignition each start (had been erratic as well) and the volts are sitting nice and steady at just shy of 14. After a test drive everything in the cluster ppears to work perfectly for the first time since I bought the car.
First moral of the story, when you open the back to replace bulbs check the green connector close to the hinge with a magnifying glass and if you already have gauge problems consider this as a possibility.
Second moral of the story, you do not need to remove the gauge needles. I know this because I thought I did, and though I carefully photographed needle position for reinstall I am out an annoying needle width on the temp and oil pressure gauges so I'll need to go back in to fix them, but might wait until I have a bulb to replace or something similar.
Defrost actuator
Months ago i did a full vacuum diagnosis and found the centre comb actuator was faulty along with the defrost actuator. I plugged these while i got around to fixing them. I was also thinking that the price for new actuators was a bit too porsche for my liking given that you only strip out the diaphragm from the new part to use into the old part so have been looking for other solutions or bargains. About three months ago i spotted a new old stock Mercedes vacuum pod on eBay for US$5 that looked like a good match though the actuator cap was pink!
Anyway last night after finishing the cluster reinstall I had a go at the defrost actuator and the short story is the Mercedes diaphragm is a perfect match and the actuator is now fixed, big grin as i watched the arm go up and down as I moved the heater control. All this with the dash and centre console in place. Here is the long form procedure if you are interested (all for a RHD S4 but would translate easily to a LHD car i think):
Remove parcel shelf
Optionally remove steering wheel (I did not but it would make it much easier if you are larger than medium sized)
lying on your back you should be able to see the base of the actuator and two of the four lugs that hold the cap on, get a screw driver onto those and work the cap off - this was fiddly and probably took 15 minutes just for that.
With a long slot end screwdriver reach up to where the actuator arm connects onto a plastic push pin on the flap arm and with the screw driver head between the plastic flap arm and the actuator arm twist and this should pop the arms apart.
Work the actuator arm down and then you will need to get out from under the dash and from the front to the left of the steering column there is a smallish gap between the column mouldings and the centre console, sort of a horizontal gap about 5 cms high and maybe 15 cm long. With a bit of fiddling you should be able to work the rubber diaphragm with arm attached out though that space. Once you have taken the old diaphragm off and put the new one on reinstallation is the reverse, i.e. feed the arm first into that gap by the steering column from the front (being careful not the split the diaphragm because it is a tight fit) and once that's in the actuator body go back under the dash and proceed from there.
Mostly its just plain tricky with such limited access and visibility. I used a head mounted light and that's probably the best option. To get the actuator arm onto the flap pin was perhaps the single hardest task, in the end i got two long extensions from my socket set and put one behind the flap arm and one on the other side of the actuator arm and just pressed them together. Very pleased to hear the click as that job took about 15 minutes as well. Total time for the replacement was about 45 -60 minutes.
I wish i could tell you the Mercedes part number but it came without one.
All in all, a pretty good two days and two annoying problems fixed for virtually no $.
09-12-2006, 09:23 PM
#2
Basic Sponsor
Rennlist
Site Sponsor
Rennlist
Site Sponsor
Jason,
Thanks for the info.
I have a replacment diaphragm for the recirc actuator, however it is slightly different in length to the defrost actuator diaphragm. Maybe I should fit one and see if it works.
I am also making molds for the remaining diaphragms on our cars.
Roger
Thanks for the info.
I have a replacment diaphragm for the recirc actuator, however it is slightly different in length to the defrost actuator diaphragm. Maybe I should fit one and see if it works.
I am also making molds for the remaining diaphragms on our cars.
Roger
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
