Tachometer was working fine until this morning when I started the car and the tachometer refused to rise above 1500rpm. The was no symptoms of failure before today. The symptoms are,
1) from idling rises to 1500rpm is fine
2) continuous increase in revs above 1500rpm causes the revs dropped to around 700rpm
3) lift-off or change-up (auto), which causes the revs to drop, causes the tachometer to rise from previous 700rpm back to 1500rpm
4) if keep constant speed, contants revs and thottle openning, the needle fluctuate a small amount (+/- 50rpm) at 1500rpm.
The car runs as normal which I guess the Engine Control Module (ECM) is operating without fault. Is there much I can do? I cannot find the location of the ECM to verify the output signal to the tacho, which is what I prefer to do before I take apart the dash to get to the back of the instrument cluster.
Many thanks,
Gazza
BTW, for Apilia's information, I have bought the strut brace from the company in Hong Kong as suggested. It costs £17.86 due to the high rate of Sterling. I would be fitting it soon and will let you know my findings.
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BTW, for Apilia's information, I have bought the strut brace from the company in Hong Kong as suggested. It costs £17.86 due to the high rate of Sterling. I would be fitting it soon and will let you know my findings.
Blimey, £17.86 !! You couldn't buy the alloy for that in the UK!
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Gazza
I think you had the workshop manual from me on a CD? This gives the wiring diagrams for your model as well as all component locations - its pretty comprehensive. The ECM is behind the lower dash over the centre tunnel. It has a plastic cover over it, you'll be able to see it if you look from the front footwell.
I can't remember where the tacho signal comes from (ECU or off a coil feed) but I suspect that its a problem with the tacho gauge unit rather than the feed.
The gauge unit will use a 'cross coil' meter movement driven from either a microcontroller (or more likely) a custom analogue driver IC. It sounds to me like one of the two cross-coils is not getting a signal - most likely due to a dry or fractured solder joint. Once you've checked for a signal then pull the cluster out and reflow all the joints on the PCB - that might well fix it.
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Yes, thanks and I have the CD. I just wasn't sure what it is from the diagram of the CD. Many thanks, Gazza.
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What does dry joint look like? I haven't seen a 9 year-old solder-joint before.
I got everything apart now, I saw that some joints appears matt grey while some are shiny silver. Are the matt grey ones the dry joints?
I have lead free silver solder at home. Are these the right type to use or do I need to get somethings else?
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Yes, the matt ones are the 'dry' ones. A good joint should look very shiny, almost as if its 'wet'.
Silver solder is no good (I think thats used in jewellery making, isn't it?). Don't use 'plumbers' solder' either! You need a good electronics grade solder with a flux. I use a halide flux solder, but you might not be able to get that. Try Maplins, or maybe a local tv/radio repair place will sell you some.
Reflow all the joints. Don't overheat the joints and don't put too much new solder on. Use a decent soldering iron (i.e. an electronics type one with a small diameter tip - not something that looks like a dirty shovel).
Come to think of it, you could take the whole thing to a local TV/video repair man and ask him just to reflow the joints for you - shouldn't cost much at all and he'll have the right stuff to do it.
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I've just had the joints reflow by a TV repair man and the tachometer is still the same. Any suggestions? Or time to find a second-hand tacho? (more like will have to buya new one from Nissan as not many QX exists in scrap yard)
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Well, if that's the case the driver IC may well have blown. From your description is definitely sounds like an electronic fault. Without electronic test equipment you are a bit stuck.
Looks like it might be time to get a price from Nissan, or try to get a s/hand one.....
If you do get a new one then send the old one to me and I'll try repairing it (if I can get hold of the driver IC).
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Got a shock from Nissan. £483.02 for a tachomter!!! I did not get a quote for a complete cluster but the guy said it will be over £1000!!!
Jap-spares has a cluster with 96k on the clock for £75 + £10 delivery + VAT = £99.88
Is that a reasonable price?
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Not a surprise really Gazza, clusters for most cars are usually incredibly expensive.
A s/hand cluster at £100 is not too bad at all.
The other option is forget your tacho (leave it faulty) and buy an aftermarket tacho to bolt on the dash somewhere (not very neat though....).
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Had some trouble finding it as most people has the 2L model and not 3L. Is there any difference between the 2L and the 3L cluster?
Jap-Spares put me to another guy who has a 3L cluster and I have placed an order on a 1998 QX 3L (auto) instrument cluster with 46k on the clock for £99.87 Hopefuly arrive tomorrow if not Friday and I'll let you know how I get on.
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Is the QX 2L and 3L both 6 cylinder engines or even four cylinders but are they the same if not the 3L cluster will not work in a 2L car if the drive chip is in the cluster not the ECU. !!
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2l and 3l litre clusters are the same. The engine and everything else is basically the same apart from cylinder bore and final drive ratio.
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