1988 XJ40 instrument cluster intermittent failure
#1
11-20-2017, 09:47 PM
1988 XJ40 instrument cluster intermittent failure
Hi folks, new owner of a 1988 XJ40.
At times the left side (oil pressure, water temp, etc.) and odometer will go dark on the instrument cluster. The right side with the trouble warnings continues to be lit at all times.
If the cluster goes dark it will come back with a light tap or two on the dash. When it is lit all data in the cluster looks like it is working correctly. Temp, pressure and voltage look like the right numbers, as does the odometer.
I am guessing there is some sort of loose connection in the back. Any suggestions on troubleshooting and repair?
At times the left side (oil pressure, water temp, etc.) and odometer will go dark on the instrument cluster. The right side with the trouble warnings continues to be lit at all times.
If the cluster goes dark it will come back with a light tap or two on the dash. When it is lit all data in the cluster looks like it is working correctly. Temp, pressure and voltage look like the right numbers, as does the odometer.
I am guessing there is some sort of loose connection in the back. Any suggestions on troubleshooting and repair?
#2
11-21-2017, 04:58 AM
Senior Member
electronic dashboard
Hello Origamisensei
an interisting article
https://www.jaguarforums.com/forum/x...ge-type-59239/
http://www.jcsovejag.com/jaguarxj/xj40_depan_tdb.php
bestregards
an interisting article
https://www.jaguarforums.com/forum/x...ge-type-59239/
http://www.jcsovejag.com/jaguarxj/xj40_depan_tdb.php
bestregards
Last edited by frenchfairplaydriver; 11-21-2017 at 05:00 AM.
The following 2 users liked this post by frenchfairplaydriver:
Don B (11-21-2017),
OrigamiSensei (11-21-2017)
#3
11-21-2017, 09:54 AM
I appreciate the reply. I had done some more research after posting the question and had seen the instrument cluster swap thread. Ordinarily I would be very enthusiastic to do that, except in this case there are two reasons for me not to.
First, I want to keep the car as original as possible. Second, although the electronics are one of the biggest concerns I had when I bought this car I actually prefer the original cluster. There's something I find fascinating and appealing about that era of electronics technology as I was born in 1965 and lived through that time. Then again, I'm an idiot that would happily own one of the early Aston Martin Lagondas with their troublesome electronics.
The additional information I have found indicated I may have a bad solder joint in the instrument cluster, whereas my original theory was a loose connector or connection. It looks like taking out the instrument cluster is not too daunting a task, and as an electrical engineer I'm not afraid to use a soldering iron to repair some connections.
If anyone wants to point to their favorite source of information on step-by-step instructions for getting to the instrument cluster and doing removal/re-installation I would be most grateful. I have found one or two on my own but if there are really good ones out there it would be good to know.
First, I want to keep the car as original as possible. Second, although the electronics are one of the biggest concerns I had when I bought this car I actually prefer the original cluster. There's something I find fascinating and appealing about that era of electronics technology as I was born in 1965 and lived through that time. Then again, I'm an idiot that would happily own one of the early Aston Martin Lagondas with their troublesome electronics.
The additional information I have found indicated I may have a bad solder joint in the instrument cluster, whereas my original theory was a loose connector or connection. It looks like taking out the instrument cluster is not too daunting a task, and as an electrical engineer I'm not afraid to use a soldering iron to repair some connections.
If anyone wants to point to their favorite source of information on step-by-step instructions for getting to the instrument cluster and doing removal/re-installation I would be most grateful. I have found one or two on my own but if there are really good ones out there it would be good to know.
#4
11-21-2017, 05:33 PM
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Hi OrigamiSensei,
Cold, cracked or starved solder joints on the circuit boards in the early XJ40 vacuum fluorescent displays is a well-known issue and very likely the cause of your problems.
Check the threads at these links:
https://www.jaguarforums.com/forum/x...working-26802/
https://www.jaguarforums.com/forum/x...ts-dead-77696/
Our member Rob Evenson is knowledgeable on this topic so you might try sending him a private message. There may be an actual phototutorial somewhere online so spend some time with google. If you don't find it at this forum, it may be at the Jag-Lovers forum.
Removing the instrument cluster (IC) is pretty simple. Remove the screws that secure the knee bolster and carefully pull or pry out the plastic "Fir Tree" fasteners that remain. I think your car probably has the telescoping steering wheel rather than the tilt wheel, so you will probably need to remove the steering wheel cowl, which requires removal of a few screws in the underside of the lower half of the cowl, and one or two screws up inside the upper cowl once the lower cowl is removed.
The IC is secured by four screws, two at each lower end. Take care on the lower right screw closest to you because the end of it may go through the top of a metal brace in the center console that is secured by a nut on the end of the screw. If you loosen the nut too far without being prepared to restrain it, it will jump into the far recesses of the center console never to be found again.
If I recall correctly, there are four electrical connectors on the back of the IC, two at the upper corners and two at the lower corners. To remove the upper connectors, pull the IC away from the dash far enough to access the connectors from above. It can help to stand outside the car and look down through the windshield to see where the connector tabs are. Squeeze the tabs on the ends of the connector, push the connector in toward the cluster to help the catches release, then pull it toward the firewall to remove it from the IC.
Removing the lower connectors is the same process, but I find it easier to reach under the IC and work by feel.
Cheers,
Don
Cold, cracked or starved solder joints on the circuit boards in the early XJ40 vacuum fluorescent displays is a well-known issue and very likely the cause of your problems.
Check the threads at these links:
https://www.jaguarforums.com/forum/x...working-26802/
https://www.jaguarforums.com/forum/x...ts-dead-77696/
Our member Rob Evenson is knowledgeable on this topic so you might try sending him a private message. There may be an actual phototutorial somewhere online so spend some time with google. If you don't find it at this forum, it may be at the Jag-Lovers forum.
Removing the instrument cluster (IC) is pretty simple. Remove the screws that secure the knee bolster and carefully pull or pry out the plastic "Fir Tree" fasteners that remain. I think your car probably has the telescoping steering wheel rather than the tilt wheel, so you will probably need to remove the steering wheel cowl, which requires removal of a few screws in the underside of the lower half of the cowl, and one or two screws up inside the upper cowl once the lower cowl is removed.
The IC is secured by four screws, two at each lower end. Take care on the lower right screw closest to you because the end of it may go through the top of a metal brace in the center console that is secured by a nut on the end of the screw. If you loosen the nut too far without being prepared to restrain it, it will jump into the far recesses of the center console never to be found again.
If I recall correctly, there are four electrical connectors on the back of the IC, two at the upper corners and two at the lower corners. To remove the upper connectors, pull the IC away from the dash far enough to access the connectors from above. It can help to stand outside the car and look down through the windshield to see where the connector tabs are. Squeeze the tabs on the ends of the connector, push the connector in toward the cluster to help the catches release, then pull it toward the firewall to remove it from the IC.
Removing the lower connectors is the same process, but I find it easier to reach under the IC and work by feel.
Cheers,
Don
Last edited by Don B; 11-24-2017 at 09:12 PM.
The following 2 users liked this post by Don B:
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#5
11-24-2017, 05:05 PM
I am thrilled to report the repair process seems to have been a success! It now looks like my gauges have power. This was the one thing I was really worried about as I don't like having gauges not working, especially in a car where I don't know the full mechanical provenance. I don't care to blow up a motor because my gauges were out.
Here's what I did, and remember mine is a 1988 so your model may be different:
1) Remove the driver's side knee bolster. On my car there were five spots for simple #2 Phillips screws with washers: one at each corner of the bolster and a fifth screw underneath immediately above the brake pedal.
2) There were five electrical connectors that I unplugged. On the driver's side of the steering column a yellow, blue and green. On the passenger side of the steering column a brown and a black.There is a sixth smaller black connector I unplugged but it looks like it goes from the instrument cluster to the trip computer and I think I could have left that alone.
3) As Don B surmised I have a steering wheel that telescopes but does not have any vertical adjustment. I pulled the steering wheel out as far as I could.
4) There are four 8mm bolts holding the instrument cluster in place. A small 1/4" socket drive fits the area quite nicely. Remove those four bolts.
5) To remove the cluster pull it straight up out of the dash and start to rotate it towards you. Maneuver the front lip over the top of the steering wheel and continue to rotate towards you. It's actually not too tight and everything comes out pretty easily.
6) I removed the large external trim pieces from the instrument cluster itself but that may not have in fact been necessary. It did make handling the electronics in the instrument cluster a little easier to handle, though. However, do not take the wood grain piece off the front of the gauges. It's not necessary.
7) I removed the back white cover from the electronics. Gently pry the tabs and work your way around the perimeter. If nobody has messed about with the instrument cluster before you may have to cut some "Lucas Seals" to get in there. I think we can safely assume your car is out of warranty, so don't sweat it. You may need to do some extra cutting around the bottom seal as it covers a tab.
8) In my car there was a red circuit board on the right behind where the gauges (voltage, oil, water, fuel) are located All of the wire bundles coming into the cluster are zip-tied to the white circuit board carrier. You will need to cut the zip tie for the bundle going to the red circuit board in order to access the back of the board.
9) Gently remove the red circuit board from the white carrier by prying the tabs loose and flip it over to expose the back side with the solder joints.
10) For my car the problem was that all of the gauges would lose power, as would the odometer display. The failure was intermittent and the gauges would sometimes light up randomly or if I would knock on the instrument cluster. As a result I surmised that my problem was a bad solder joint related to the power on the red circuit board. Therefore I assumed my bad solder joint would be somewhere on the transformer or on a wide power/ground trace.
11) Using a soldering iron I carefully reflowed and added solder to each of the connections on the transformer and did the same for any connection related to a wide trace on the circuit board. I did not mess with any other thin traces due to the specific nature of my problem.
12) I replaced the red circuit board into its original spot and replaced the white zip tie with a new standard sized white one that matches OEM quite nicely.
13) I then reassembled the instrument cluster. back into its original single unit.
14) In the reverse manner of removal maneuver the instrument cluster back over the steering wheel and rotate it into place as you set it down in the recess.
15) Re-install the four 8mm bolts.
16) Re-connect the connectors., With the color coding and looking at how the connectors are made it is not difficult.
17) Replace the knee bolster.
Next up: that stupid bulb failure light.
Here's what I did, and remember mine is a 1988 so your model may be different:
1) Remove the driver's side knee bolster. On my car there were five spots for simple #2 Phillips screws with washers: one at each corner of the bolster and a fifth screw underneath immediately above the brake pedal.
2) There were five electrical connectors that I unplugged. On the driver's side of the steering column a yellow, blue and green. On the passenger side of the steering column a brown and a black.There is a sixth smaller black connector I unplugged but it looks like it goes from the instrument cluster to the trip computer and I think I could have left that alone.
3) As Don B surmised I have a steering wheel that telescopes but does not have any vertical adjustment. I pulled the steering wheel out as far as I could.
4) There are four 8mm bolts holding the instrument cluster in place. A small 1/4" socket drive fits the area quite nicely. Remove those four bolts.
5) To remove the cluster pull it straight up out of the dash and start to rotate it towards you. Maneuver the front lip over the top of the steering wheel and continue to rotate towards you. It's actually not too tight and everything comes out pretty easily.
6) I removed the large external trim pieces from the instrument cluster itself but that may not have in fact been necessary. It did make handling the electronics in the instrument cluster a little easier to handle, though. However, do not take the wood grain piece off the front of the gauges. It's not necessary.
7) I removed the back white cover from the electronics. Gently pry the tabs and work your way around the perimeter. If nobody has messed about with the instrument cluster before you may have to cut some "Lucas Seals" to get in there. I think we can safely assume your car is out of warranty, so don't sweat it. You may need to do some extra cutting around the bottom seal as it covers a tab.
8) In my car there was a red circuit board on the right behind where the gauges (voltage, oil, water, fuel) are located All of the wire bundles coming into the cluster are zip-tied to the white circuit board carrier. You will need to cut the zip tie for the bundle going to the red circuit board in order to access the back of the board.
9) Gently remove the red circuit board from the white carrier by prying the tabs loose and flip it over to expose the back side with the solder joints.
10) For my car the problem was that all of the gauges would lose power, as would the odometer display. The failure was intermittent and the gauges would sometimes light up randomly or if I would knock on the instrument cluster. As a result I surmised that my problem was a bad solder joint related to the power on the red circuit board. Therefore I assumed my bad solder joint would be somewhere on the transformer or on a wide power/ground trace.
11) Using a soldering iron I carefully reflowed and added solder to each of the connections on the transformer and did the same for any connection related to a wide trace on the circuit board. I did not mess with any other thin traces due to the specific nature of my problem.
12) I replaced the red circuit board into its original spot and replaced the white zip tie with a new standard sized white one that matches OEM quite nicely.
13) I then reassembled the instrument cluster. back into its original single unit.
14) In the reverse manner of removal maneuver the instrument cluster back over the steering wheel and rotate it into place as you set it down in the recess.
15) Re-install the four 8mm bolts.
16) Re-connect the connectors., With the color coding and looking at how the connectors are made it is not difficult.
17) Replace the knee bolster.
Next up: that stupid bulb failure light.
#6
11-30-2021, 10:12 AM
Junior Member
I had, and now have fixed, this same problem! 1988 VandenPlas (XJ6/XJ40 sedan)
there is a “power supply” buried inside the instrument cluster that fails. It can fail slow & erratic, or it can fail quick & completely. Either way you lose the the green bar graph displays (fuel; oil; temp; volts) and the green outputs across bottom (mileage; blinkers; transmission position) the Analog gauge continues to work (speed; rpm)
I found a shop in Pennsylvania that can open these up and solder in new power supplies! Thus saving your old instrument cluster and prevent need to rewrite a different model year replacement.
Powl’s Speed Meter & Auto Care Center
717-898-2552
there is a “power supply” buried inside the instrument cluster that fails. It can fail slow & erratic, or it can fail quick & completely. Either way you lose the the green bar graph displays (fuel; oil; temp; volts) and the green outputs across bottom (mileage; blinkers; transmission position) the Analog gauge continues to work (speed; rpm)
I found a shop in Pennsylvania that can open these up and solder in new power supplies! Thus saving your old instrument cluster and prevent need to rewrite a different model year replacement.
Powl’s Speed Meter & Auto Care Center
717-898-2552
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