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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 |