09-08-2022, 08:07 AM
Been working on sorting out some issues with my fathers 1994 T4 SWB Caravelle. Most annoying one has been the instrument cluster with the fuel gauge and also the temp gauge reading erratically and then not at all with out a bash in the dash. This has gotten worse over the years. The mechanics refuse to touch the dash as they say is it a nightmare. Haven't really found it that bad on the other side of fixing it.
Below is a couple of articles that have helped to sort it. I might add we managed to do it with out taking off the wheel but it is a lot harder, especially the surround. I suspect just the wheel off is easier than taking off the indicators and wiper stalks, which might be asking for trouble but does give more access.
I might add, if you need to access things behind the dash that surround out gives lots of access in behind the centre of the panel too.
Not my info, just reproduced and full credit to the guys that saved me a lot of hell. The links may not work.
http://www.vwbooks.co.uk/vw_info/t4_gauges.htm
Wibbly, Wobbly Gauges
Text & Pictures - Rod Sleigh - Article originally published for Volkswagen Owners Club (GB) in 2003
New - Test procedure for the voltage regulator - Opens as a pdf in a new window - 802kb
An inherent problem with Volkswagen T4 Transporter
Fuel & Temperature Gauges.
I believe that the problem of wrong and variable reading Fuel & Temperature gauges can exist on all Volkswagen T4 Transporters with analogue mileage readout. (Up to 31st December 1996?)
From experience the problem is caused by cracked solder joints between the instrument cluster printed circuit board and the socket that holds the voltage regulator. The reason for this failure seems to be that the voltage regulator is fixed solidly to its heat sink and the body of the instrument cluster whilst its socket can vibrate on the unsecured printed circuit board. With instrument technicians soldering tools this is easily repaired, cost is almost nil. Here is how.
Job well done....
You may like to read comments about this article and further problems with this dash panel from an Australian reader in 2009.
Rod Sleigh. (Anyone with any queries about this problem please email me however be aware that I wrote this procedure in 2003 and memories get rusty.)
Copyright © 2003-2016 Rod Sleigh - All Rights Reserved
An email from Michael Donohue in New South Wales, Australia - October 2009
Dear Rod
Just a quick Email to thank you for your great information on the instrument panel/gauge problem on the 1994 VW T4 Transporter. I down loaded your photos and article (wibbly, wobbly gauges), as an inspiration to fix my own gauges, which drove me crazy for about 12 months before I (and your kind information) fixed the problem.
Symptoms: (1) My cooling system lamp stayed flashing all the time, occasionally going out, but irritatingly at random coming on again, regardless of the coolant level.
(2) The water temp & fuel gauges would work infrequently, assisted to do so only by thumping the top of the dash.
(3) The fuel gauge occasionally worked on its own, only to read incorrectly at other times, I ran out of fuel on a quarter tank.
(4) The instrument lights stopped working completely.
(5) The blue high beam light worked on low beam only.
(6) The most irritating however, was the instrument lights dimmer (rheostat) which would, when operated, cause the water temp & fuel gauge, oil light, hi beam light & tacho to act crazy.
The need to nurse the vehicle along for 12 months without good instruments, was a truly gut wrenching experience. Due to work commitments I just did not have the time to take it off the road & repair it.
In the end the engine appeared (according to the gauges) to suffer a catastrophic over-heat, with high water temp, the oil light flashing and the oil low pressure ( & over 2250 RPM) buzzer ringing in my ears, I limped on home, nerves frayed and seriously considered setting fire to the bastard of a thing. When I arrived home I discovered the 'cooling system branch fitting’ on the passengers side of the head had failed and was leaking. This no doubt started the cascading failure episode. There was thankfully still adequate coolant in the system and after replacing the part gained integrity once again to the cooling system. It was in hind sight a good thing because it forced my hand to do the much needed repair to the instruments.
Using your photos and article as a guide I successfully removed, did a fault-find and repaired the instrument panel. I found the 6 voltage regulator soldered joints cracked just as you advised, so I resoldered them. It partly solved the problem in as much as the water temp and fuel gauge worked for 2 days then quit again.
Pulling the instrument PCB out again and upon closer examination (4 hours later) under a Mag Lamp I discovered what turned out to be the main problem.
The 24 pin plug which enters the rear of the PCB engages a 24 pin socket which consists of 24 stakes that are soldered through the PCB. 20 of these stakes had a microscopic hairline crack, which when first viewed appeared to be just a shadow. The cracks must have caused the intermittent operation of the instrument panel. Although at first the cracks appeared too small to be so significant, the true fault lay in the WHY it failed.
The failed socket is serviced by a plug which in turn is captured by the wiring loom that feeds the back of the instrument panel. The offending wiring loom rises nearly vertical from the rear of the fuse box and on approach to the instrument panel, lies across and is ineffectively clipped to the steering column support bracket. Over time (the vehicle is 16 years old) due to gravity & vibration, it would appear the loom slowly slides downwards and loads up the plug and socket causing the socket stakes to fracture around their respective soldered joints. The frustrating, intermittent and progressively terminal behavior comes about after the unrestrained plug is inserted, the vehicle is driven for a while, the loom once again loads the socket and exacerbates the hairline fracture, opening it up to a point of non conductivity-hence crazy instrument readings.
I resoldered the stakes, retaped the loom (to avoid chafe) lifted it gently and reaffixed it with cable ties to the steering bracket, made absolutely sure the plug and socket mated correctly (listen and feel them 'snap together') applied a strain relief 'plastic coated twist tie' around the loom at the back of the plug and tethered it to the small plastic strain relief eyelets on the back of the instrument panel adjacent to the socket.
This belt and braces approach has worked well. I now have all my instruments working correctly, the instrument lights work and dim in sympathy with the rheostat action, the hi-beam light works on hi-beam only, the oil and water temp lights do not come on while driving, the fuel gauge works accurately and my nerves are somewhat more settled.
I did as a further sanity measure; install a complete set of ancillary, independent gauges, consisting of water & oil temperature, oil pressure and battery voltage, as well as two temperature probes strategically placed on significant engine parts. Should the original gauges fail again, I can fly home on my own instruments. The aforementioned took approx forty hours of intermittent work over 4 weeks to achieve.
I trust some of this may be of interest to you and in some way shows just what a positive and worthwhile affect your original article has had on those of us who read it.
Many thanks and kind regards
Michael Donohue
Lake Macquarie, NSW. Australia.
Below is a couple of articles that have helped to sort it. I might add we managed to do it with out taking off the wheel but it is a lot harder, especially the surround. I suspect just the wheel off is easier than taking off the indicators and wiper stalks, which might be asking for trouble but does give more access.
I might add, if you need to access things behind the dash that surround out gives lots of access in behind the centre of the panel too.
Not my info, just reproduced and full credit to the guys that saved me a lot of hell. The links may not work.
http://www.vwbooks.co.uk/vw_info/t4_gauges.htm
Wibbly, Wobbly Gauges
Text & Pictures - Rod Sleigh - Article originally published for Volkswagen Owners Club (GB) in 2003
New - Test procedure for the voltage regulator - Opens as a pdf in a new window - 802kb
An inherent problem with Volkswagen T4 Transporter
Fuel & Temperature Gauges.
I believe that the problem of wrong and variable reading Fuel & Temperature gauges can exist on all Volkswagen T4 Transporters with analogue mileage readout. (Up to 31st December 1996?)
From experience the problem is caused by cracked solder joints between the instrument cluster printed circuit board and the socket that holds the voltage regulator. The reason for this failure seems to be that the voltage regulator is fixed solidly to its heat sink and the body of the instrument cluster whilst its socket can vibrate on the unsecured printed circuit board. With instrument technicians soldering tools this is easily repaired, cost is almost nil. Here is how.
- Whilst it is normal to insist that the battery is disconnected before any work on electrical items, it is not necessary but preferable for this job. It is however an unwritten rule to remove (or tape up) your watch and rings before working close to live electric components.
- Set steering wheel to 12 o'clock position so that it can be replaced correctly without any other adjustments. If you have an airbag stop now and refer the job to a workshop. If not continue as follows. Pull off horn push carefully! It is snapped into four rubber sockets but may well come apart dropping the contact separating springs on the floor. It is worth reassembling the two halves before proceeding too far to preserve the springs and do the job whilst you remember what's what.
- Remove the two connecting wires and put horn push to one side. Picture. Remove large nut that holds wheel to column and pull off wheel ensuring that it is still at 12 o'clock position. Put wheel to one side taking care not to mark upholstery / carpets with the grease on the underside.
- Remove upper and lower plastic shrouds from the column switch mechanisms, these are held together and to the column by three screws, two marked (2) self tapping and one marked (1) set screw see Picture. The lower shroud will unclip from its upper partner and drop away, put it to one side. The upper section WILL come out over the switch arms if they are both moved to their lowest position.
- Unscrew three screws marked (3), Picture, but don't pull them out as they help to keep the two switch sections together and correctly aligned. Remove three or four (depending on vehicle options) plugs that connect wiring looms to them. Picture. Each plug has two clips, one attached and one that is part of the housing each has to be sprung to extract the plug. The dual switch assembly will now lift off the column stub. Put it to one side.
- The instrument surround is held in place with two screws marked 2 in Picture, remove these and pull the plastic surround towards you and lift away. The instrument cluster is now before you.
- The instrument cluster is held in place by a screw each side, see Picture showing a screwdriver in place at the location of the left one (RHD vehicle). Remove both screws being careful not to drop them into the lower parts of the dash and fuse box.
- Now remove the cover from the fuse box, it's behind the little oddments tray above the driver's right knee, usually removed by turning the slotted knob through 90 degrees and hinging down. Then lift off the hinge pins. Now reach up behind the instrument cluster. Locate the speedometer cable at its connection to the instrument cluster. Squeeze the plastic lugs on the sides of connector to release it, push the cable away from the back of the instrument cluster.
- Tilt the right side of the cluster towards you, locate the electrical connector plug. Again removal is by squeezing together two plastic clips, squeeze and pull from the instrument cluster. After the instrument cluster has been removed the shape of these connectors can be seen in this Picture. The unit is now free to take to the workshop.
- Now working on a bench top with good lighting the instrument cluster can be disassembled to access the point of the trouble. Unscrew the two screws located either side of the instrument cluster Picture, and prise the retaining clips clear to part cover from the body. Take care not to touch the inside of the plastic window with finger marks, you will regret it for ever!
- Now lift off the two gauges and clock, the clock may require a little more pressure Picture. The speedometer also comes away from the base in a similar manner.
- The printed circuit board can now be removed from the housing by removing the heat sink screw from the voltage regulator (Your target) and the clips that hold the wiring loom connector socket to the housing. As you lift the board out please take care of the ribbon cable that feeds the illumination bulbs, this can be unplugged from the board.
- Now with a powerful magnifying glass you will probably see fine cracks in the soldering. Remove the voltage regulator from its socket before applying heat, noting which way around it fits for replacement. A small instrument soldering iron will enable you to re-solder these six connections.
- I can now offer no better than the conventional instructions for replacing all these bits into your vehicle. Reassembly is the reverse of disassembly. It is worth checking that the gauges and warning lights all correctly work before fitting the instrument surround and noting that there are two clips to locate the bottom of the surround as it is pushed into position. Again before fitting the steering wheel but after fitting and connecting the switch assemblies test that all of their functions work correctly. The last operation after fitting and tightening the steering wheel is to connect the horn push. Careful examination will reveal + and - markings on both ends of the wire connections, connect like for like.
Job well done....
You may like to read comments about this article and further problems with this dash panel from an Australian reader in 2009.
Rod Sleigh. (Anyone with any queries about this problem please email me however be aware that I wrote this procedure in 2003 and memories get rusty.)
Copyright © 2003-2016 Rod Sleigh - All Rights Reserved
An email from Michael Donohue in New South Wales, Australia - October 2009
Dear Rod
Just a quick Email to thank you for your great information on the instrument panel/gauge problem on the 1994 VW T4 Transporter. I down loaded your photos and article (wibbly, wobbly gauges), as an inspiration to fix my own gauges, which drove me crazy for about 12 months before I (and your kind information) fixed the problem.
Symptoms: (1) My cooling system lamp stayed flashing all the time, occasionally going out, but irritatingly at random coming on again, regardless of the coolant level.
(2) The water temp & fuel gauges would work infrequently, assisted to do so only by thumping the top of the dash.
(3) The fuel gauge occasionally worked on its own, only to read incorrectly at other times, I ran out of fuel on a quarter tank.
(4) The instrument lights stopped working completely.
(5) The blue high beam light worked on low beam only.
(6) The most irritating however, was the instrument lights dimmer (rheostat) which would, when operated, cause the water temp & fuel gauge, oil light, hi beam light & tacho to act crazy.
The need to nurse the vehicle along for 12 months without good instruments, was a truly gut wrenching experience. Due to work commitments I just did not have the time to take it off the road & repair it.
In the end the engine appeared (according to the gauges) to suffer a catastrophic over-heat, with high water temp, the oil light flashing and the oil low pressure ( & over 2250 RPM) buzzer ringing in my ears, I limped on home, nerves frayed and seriously considered setting fire to the bastard of a thing. When I arrived home I discovered the 'cooling system branch fitting’ on the passengers side of the head had failed and was leaking. This no doubt started the cascading failure episode. There was thankfully still adequate coolant in the system and after replacing the part gained integrity once again to the cooling system. It was in hind sight a good thing because it forced my hand to do the much needed repair to the instruments.
Using your photos and article as a guide I successfully removed, did a fault-find and repaired the instrument panel. I found the 6 voltage regulator soldered joints cracked just as you advised, so I resoldered them. It partly solved the problem in as much as the water temp and fuel gauge worked for 2 days then quit again.
Pulling the instrument PCB out again and upon closer examination (4 hours later) under a Mag Lamp I discovered what turned out to be the main problem.
The 24 pin plug which enters the rear of the PCB engages a 24 pin socket which consists of 24 stakes that are soldered through the PCB. 20 of these stakes had a microscopic hairline crack, which when first viewed appeared to be just a shadow. The cracks must have caused the intermittent operation of the instrument panel. Although at first the cracks appeared too small to be so significant, the true fault lay in the WHY it failed.
The failed socket is serviced by a plug which in turn is captured by the wiring loom that feeds the back of the instrument panel. The offending wiring loom rises nearly vertical from the rear of the fuse box and on approach to the instrument panel, lies across and is ineffectively clipped to the steering column support bracket. Over time (the vehicle is 16 years old) due to gravity & vibration, it would appear the loom slowly slides downwards and loads up the plug and socket causing the socket stakes to fracture around their respective soldered joints. The frustrating, intermittent and progressively terminal behavior comes about after the unrestrained plug is inserted, the vehicle is driven for a while, the loom once again loads the socket and exacerbates the hairline fracture, opening it up to a point of non conductivity-hence crazy instrument readings.
I resoldered the stakes, retaped the loom (to avoid chafe) lifted it gently and reaffixed it with cable ties to the steering bracket, made absolutely sure the plug and socket mated correctly (listen and feel them 'snap together') applied a strain relief 'plastic coated twist tie' around the loom at the back of the plug and tethered it to the small plastic strain relief eyelets on the back of the instrument panel adjacent to the socket.
This belt and braces approach has worked well. I now have all my instruments working correctly, the instrument lights work and dim in sympathy with the rheostat action, the hi-beam light works on hi-beam only, the oil and water temp lights do not come on while driving, the fuel gauge works accurately and my nerves are somewhat more settled.
I did as a further sanity measure; install a complete set of ancillary, independent gauges, consisting of water & oil temperature, oil pressure and battery voltage, as well as two temperature probes strategically placed on significant engine parts. Should the original gauges fail again, I can fly home on my own instruments. The aforementioned took approx forty hours of intermittent work over 4 weeks to achieve.
I trust some of this may be of interest to you and in some way shows just what a positive and worthwhile affect your original article has had on those of us who read it.
Many thanks and kind regards
Michael Donohue
Lake Macquarie, NSW. Australia.
A new beginning. 
+
1975 Kombi The Doctor
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+1975 Kombi The Doctor
1976 Dual Cab Bumble Bee
1974 Microbus Matilda (parts bus)
