720 4x4 - Fuel & Temp Gauges Suddenly Stop Working

[gone2long]

Hi again.

 

Problems in addition to the rattling noted in another post are as follows:

 

As mentioned in an related post a few months back, I had the truck recently completely rewired only about 6 months ago.  One day, about 1 month after the re-wiring,  I noticed that the fuel gauge had simply stopped working, and so had the temperature gauge, which is really worrisome.  I haven't been using the truck much, so I've simply ignored these faults, but I will soon need to take her on a long drive and need to solve this issues ASAP.

.

 

I checked the related fuses, and they were OK.  What could have caused these problems, and what to do about them?

 

Any and all comments appreciated.

 

G2L

[Lockleaf]

Both gauges are supplied by a built in voltage regulator in the gauge cluster.  I would start looking there.

[gone2long]

HI Lockleaf,

 

OK, time to show my ignorance.  Not sure what you mean by the "gauge cluster".  Where is this found?  Do you have a photo of one?

 

I am wondering if, during the rewiring, the electrician simply forgot to add the voltage regulator to the mix.  It does make sense that the voltage regulator you note could be the problem, because it seems that both systems suddenly stopped functioning at exactly the same time.

 

Any further assistance or advice would be greatly appreciated.

 

Thanks,

 

G2L

[gone2long]

As an after thought:  If a missing or malfunctioning voltage regulator were the problem, wouldn't the fuses to these gauges fry?  I noted above that the fuses are OK.

[robert davis]

the gauge cluster is the "box" that holds all your gauges. your speedo, fuel gauge, ect. to remove this you need to remove the bezel or plastic ring held in by 2 screws and 2 clips after that you need to remove 2 more screw holding the actual "box". after you need to reach under the dash and pull the plugs behind the cluster ( you will need to remove a metal plate screwed and bolted to the bottom of the dash) after that you can pull the box out and take a look at it. i would recommend pull the speedometer cable off the back of the cluster first because after you will be able to pull it a little and take the other plugs out from the front rather than trying to reach behind the dash 

[gone2long]

On ‎4‎/‎23‎/‎2019 at 3:47 AM, Lockleaf said:

Both gauges are supplied by a built in voltage regulator in the gauge cluster.  I would start looking there.

Clarification:   I think I get what you mean by the gauge cluster, but if I am correct, that is just a series of gauges on the dashboard. The question that I am actually asking is where would the voltage regulator be found, and what would it look like?  Would it be under the dash on the cabin side of the firewall, or under the hood?  Got a photo of one?

 

 

 

 

[Lockleaf]

The gauges are all hooked together in a complete plastic housing (the cluster) that comes out.  The regulator is inside that housing.

 

Google 720 gauge cluster if you want to see the assembly.

[gone2long]

4 hours ago, robert davis said:

the gauge cluster is the "box" that holds all your gauges. your speedo, fuel gauge, ect. to remove this you need to remove the bezel or plastic ring held in by 2 screws and 2 clips after that you need to remove 2 more screw holding the actual "box". after you need to reach under the dash and pull the plugs behind the cluster ( you will need to remove a metal plate screwed and bolted to the bottom of the dash) after that you can pull the box out and take a look at it. i would recommend pull the speedometer cable off the back of the cluster first because after you will be able to pull it a little and take the other plugs out from the front rather than trying to reach behind the dash 

Thanks.  Google 720 gauge cluster an found a pretty good link posted on  Nico club,, which details the whole procedure.  Wondering if you wrote it.  Best, G2L

[gone2long]

3 hours ago, Lockleaf said:

The gauges are all hooked together in a complete plastic housing (the cluster) that comes out.  The regulator is inside that housing.

 

Google 720 gauge cluster if you want to see the assembly.

Did the deed and found some good stuff.  See my reply to Robert for more.  Thanks for the tip

[datzenmike]

On 4/22/2019 at 9:22 AM, gone2long said:

 I had the truck recently completely rewired only about 6 months ago.  One day, about 1 month after the re-wiring,  I noticed that the fuel gauge had simply stopped working,

 

If this is true it was wired well enough. If fuses are good then most likely the regulator. I'll post a picture of the back of the gauges where it is.

[gone2long]

Thanks.  Much appreciated.

[datzenmike]

 

 

You'll have to take the gauge cluster out, but at least the speedo clips on, on the 720. Disassemble and look for points or contacts wrapped with a small white wire like the picture. (middle center left with the adjusting screw) I forget what gauge it was behind. Fold a thin strip of very fine emery cloth, open the points, place the emery paper between and let close, draw the paper through several times to polish and clean them.

 

Hang on, I see you have the early 720 with the square gauges. Haven't seen them but very likely you will find something similar in there.

[robert.davis]

5 hours ago, gone2long said:

Thanks.  Google 720 gauge cluster an found a pretty good link posted on  Nico club,, which details the whole procedure.  Wondering if you wrote it.  Best, G2L

lol no that wasnt me but i recently re-did my cluster if you need any help or have a question about the removal feel free to ask 🙂

[gone2long]

12 hours ago, robert.davis said:

lol no that wasnt me but i recently re-did my cluster if you need any help or have a question about the removal feel free to ask 🙂

Thanks mate.  Will do. : )

[gone2long]

15 hours ago, datzenmike said:

 

 

You'll have to take the gauge cluster out, but at least the speedo clips on, on the 720. Disassemble and look for points or contacts wrapped with a small white wire like the picture. (middle center left with the adjusting screw) I forget what gauge it was behind. Fold a thin strip of very fine emery cloth, open the points, place the emery paper between and let close, draw the paper through several times to polish and clean them.

 

Hang on, I see you have the early 720 with the square gauges. Haven't seen them but very likely you will find something similar in there.

Yeah, have the square gauges, which is one reason that the above was a bit confusing.  Other reason is my formidable ignorance.  Thanks  : )

[gone2long]

12 hours ago, robert.davis said:

lol no that wasnt me but i recently re-did my cluster if you need any help or have a question about the removal feel free to ask 🙂

 

BTW, when I had a problem with the speedometer, going up to 40k and stopping there, a local mechanic pulled the gauge cluster and told me that the speedometer cable was "broken".  Well, the cable was not broken, but it was disconnected from the cluster assembly.  Is it possible to "break" the cable connection when removing or trying to re-connect the gauge cluster?

 

The Nico club  procedure detailed how tricky it was to re-connect the speedometer cable due to the limited space available to do so.  Maybe the mechanic who pulled the gauge cluster was not able to reconnect the speedometer cable when he tried to reinstall the cluster, so he simply told me that the cable was "broken".  Sorry,  but this is the kind of crazy shit I have to deal with out here in Asia.

 

Whaddaya think?

[robert.davis]

2 hours ago, gone2long said:

 

BTW, when I had a problem with the speedometer, going up to 40k and stopping there, a local mechanic pulled the gauge cluster and told me that the speedometer cable was "broken".  Well, the cable was not broken, but it was disconnected from the cluster assembly.  Is it possible to "break" the cable connection when removing or trying to re-connect the gauge cluster?

 

The Nico club  procedure detailed how tricky it was to re-connect the speedometer cable due to the limited space available to do so.  Maybe the mechanic who pulled the gauge cluster was not able to reconnect the speedometer cable when he tried to reinstall the cluster, so he simply told me that the cable was "broken".  Sorry,  but this is the kind of crazy shit I have to deal with out here in Asia.

 

Whaddaya think?

not sure on that one but the way i did my speedo cable was slightly easier because i tested fitted it when the dash was out so i knew exactly how to do it but the easiest way i found is to have someone push the cable towards you from inside the the hood its near the brake booster just move the cable from the inside to figure out which cable is the speedo cable and he can even pull it back initially to get it out of the way putting the cluster itself in but find out where the "clip" is on the tip of the cable so you can push that and pull it theres a big "nipple" on the back of the cluster the speedo connects too on the circle gauges cluster not 100% sure on the square one but i imagine it being really similar 

[datzenmike]

This!

 

There is slack so push some inside the cab and you can clip it on the back of the gauge cluster.

[gone2long]

On 4/26/2019 at 2:29 AM, robert.davis said:

not sure on that one but the way i did my speedo cable was slightly easier because i tested fitted it when the dash was out so i knew exactly how to do it but the easiest way i found is to have someone push the cable towards you from inside the the hood its near the brake booster just move the cable from the inside to figure out which cable is the speedo cable and he can even pull it back initially to get it out of the way putting the cluster itself in but find out where the "clip" is on the tip of the cable so you can push that and pull it theres a big "nipple" on the back of the cluster the speedo connects too on the circle gauges cluster not 100% sure on the square one but i imagine it being really similar 

Hmmm, i seem to remember the nipple on the cable end, but I don't remember seeing the clip.  Could the clip have popped off after hitting a bump, thus causing the cable to disconnect and the speedometer no longer functioning?  The plastic is very old and probably very brittle from engine heat and years of tropical sunlight beating down on the dash and hood.