electrical ?

[dscott]

I was driving along in my cruiser today bj70 when my temp guage and fuel guage shot up to full and very hot ,but came back down just as fast to normal again ,i stopped and checked water and it was perfect , any idea,s got me stuffed

[mc dave]

Its gotta be a short somewhere. The fact that 2 guages went together either makes it a lot easier or very hard to trace.

I'd start by looking behind the instrument cluster and follow the wires from there. The theory being that you'll find the problem before the wires split off.

Other thing to keep in mind, it may not happen again for 6 months!!!

Wait till it happens a few more times before you rip your rig to pieces and start tearing your hair out. If / When it does happen, see if it stops when you whack the dash with your hand!!!

[dow50r]

From memory these two gauges are linked in the back of the dash, so i would think a wire has earthed.
Andrew

[dumbdunce]

the problem is common to lots of 7x series cruisers. the fuel and temp gauges share a voltage regulator which sometimes kinda goes a bit mental, but they always seem to come good again within a few seconds.

Iv'e pulled several clusters apart trying to rectify it (after a couple of heart-attack moments seeing the temp gauge pegged) but don't think i ever solved it.

sorry no solution, but it's not really tnything you need to worry about.

cheers

Brian

[Area54]

If you are unable to solve the prob you can always fit an auxilliary temp gauge for added insurance.

[Bluey]

the problem is common to lots of 7x series cruisers. the fuel and temp gauges share a voltage regulator which sometimes kinda goes a bit mental, but they always seem to come good again within a few seconds.

Iv'e pulled several clusters apart trying to rectify it (after a couple of heart-attack moments seeing the temp gauge pegged) but don't think i ever solved it.

is that voltage regulator like what is used in dc electrics ie computers etc (convert one dc voltage to another) or something else entirely? shouldn't it be a matter of replacing this regulator ie if that is what is fault.

[dumbdunce]

is that voltage regulator like what is used in dc electrics ie computers etc (convert one dc voltage to another) or something else entirely? shouldn't it be a matter of replacing this regulator ie if that is what is fault.

no from memory it is a cheesy bi-metal mechanical "regulator", and it is an integral part of the (trying to remember!) fuel gauge - ie it's not a discrete component but part of one of the gauges. I think those 2 gauges run at about 7 volts but if the regulator "welds" closed suddenly they get 12v so they peg.

don't trust any of that as gospel though, it's over 5 years since I had one apart trying to fix that exact problem, all I know is (1) I couldn't fix it (2) my current 70 still does it from time to time.

whenever I look down and see the temp gauge pegged I have a heart attack moment but I calm down when I see the fel gauge off the scale too.

cheers

Brian

[Bluey]

stupid question maybe, but if it is 7 volt reg, why not exchange for discrete regulator. i only ask as the middy im looking to buy does just this, both guages flick up to high intermittantly. actually this bi-metal thing be used in other cars???, this same fault used to happen in the missus's gemini too.

dick smith has 8volt reg LM7808CT +8V 1A V/Regulator $1.35, or adjustable reg LM317T 1.2-37V 1.5A Adj V/Reg $2.04

[dumbdunce]

yeh maybe. but I am really just guessing at the 7v thing. solid state regulators can be biased up so if it has to be 7v you can use a 7805 with a resistor on the centre pin to get 6 (or 7 or 8 or 9) volts from them, too.


also I really don't remember if it's possible to separate the regulator bit out of the gauge. if you do decide to pull it apart I'd be interested to hear how you go. it's not all that difficult to pull the gauge cluster off a 70 series, but from memory what was difficult was testing stuff with the multimeter while the auge cluster is plugged in to the wiring harness.

[Bluey]

also I really don't remember if it's possible to separate the regulator bit out of the gauge. if you do decide to pull it apart I'd be interested to hear how you go. it's not all that difficult to pull the gauge cluster off a 70 series, but from memory what was difficult was testing stuff with the multimeter while the auge cluster is plugged in to the wiring harness.

will do. going to buy manual, see if it as hopeless as any other manual when it comes to electricals. why is it that a manual can have really going step by step instructions and pics for mechanicals, and for electrical just a few lines and square box for lamp/switch/reg/alt/etc rant rant rant.

as with testing, i've noticed that before. rite pain in the ass

[dumbdunce]

the electrical sections in the manuals are hopeless. I can scan/email you the relevant wiring diagrams if you like but they're not real helpful.

[ToNkA]

To ad to this.

Same thing happening in my 84 hilux. Only the temperature gauge, its jumping all over the place. Not all the time but becomming more apparent.

Anywhere in particular I should look for a short in the wiring?

[Bluey]

the electrical sections in the manuals are hopeless. I can scan/email you the relevant wiring diagrams if you like but they're not real helpful.

nah, not at the moment anyway. i'll buy manual anyway, need more help with mechanics than electrics, so works out ok. just need to spend needless hours trying to work out whats actually in the "box". schematics or proper wiring diagrams would be so much better. found searching online sometimes brings up useful info. mite try tonight when have time on this topic.

Tonka, no idea on exactly what to look for as not had this myself yet. if wiring fault try to remove cluster from dash but wires still connected, then start poking/prodding/pulling wires till something happens

actually dd, could you email something and i'll get started looking. whenever you have a chance.

Cheers
Lance

email address is:
[url]lbeament@dodo.com.au[/url]