Toyota troop carrier HZJ75 Problem

Gday


I was just wondering if anybody with a toyota has experienced this happening, my vehicle is a Toyota troop carrier HZJ75 and has the 4.2 ltr 1 HZ diesel engine, for awhile now every now and then the temperature gauge would suddenly go up quite high, the first time I saw this I pulled straight off the road thinking that I had burst a hose or that the fan belt had broken.

After inspecting it I found everything normal and then when looking back at the gauge I saw that it had gone back to normal running temperature???, anyway after that I fitted a new thermostat, and later again when the timing belt was due for replacement fitted a new water pump, the radiator was serviced and re soldered after a small crack appeared in the top tank, so there was really nothing else left to replace except for the temperature gauge sender unit, which I have not done as yet, and maybe I will have the fan hub (fluid filled type) checked as well, but that feels normal as far as resisitance goes.

Anyway the other day while driving along both the fuel gauge for the front tank which was about half full and the temperature gauge both went up together, each going completely to the top limit of the gauges, I nearly had a heart attack I can tell you, I immediately pulled off the road and left the engine running while I had a quick look under the bonnet, no steam, no bubbling, no nothing???, everything normal and the engine was not that hot that you could not lay your hand on it, so now I am wondering wtf is going on with it?, damn gremlins.

My guess is that there is obviously some relation between the temp gauge and the fuel gauges in the wiring, and I have heard of this before with other vehicles that have some component in the system that serves both gauges, or that maybe there is some part of the wiring that is shorting out, or rather earthing that shouldnt be?, has anybody encountered this sort of thing before? or have any ideas on where to start to look?

Any auto elecs out there?

Thanks in advance


stayyerAU

.

No auto sparky, but have had similar probs b4 with my Mav,, narrowed it down to a lack of earth, so chech all your body, engine and battery earth connections,, ensuring there is a definaste earth, if need be do a continuity test with a meter,, hope this helps

Happy Hunting
Steve and Lea

Hi stayerAU

some ideas, 1/ could be a loose earth wire in the dash behind the gauges (6 to 8 screws from memery to get it out) try turning on all lights and blinkers put foot on brake and see if dash lights fliker a lot this can show poor earth
2/ when you have the dash out follow wires back from gauges to where they go through the firewall and check wires for damage maybe rubbing on metal and giveing you a short some times

have seen this happen before and can be a pain to find. easy way is to check wire from sender's to gauges they may contact some where

all else fail's how much do you like the car and do you have a match LOL

good luck I hope you find it PM me if you get stuck Allan in vic

stayerAU
You have a short,id say a cable harnes is rubbing somewhere and is close to grounding out. Check all harness running thru the fire wall look for contact on the metal chassis.
This would be what id be looking for, incorrect grounding will only stop things working (open circuit) what you are describing is some thing that is only just grounding out,also is this happening when it is wet ???? could explain the randomness of the fault.
Get hold of a electrical manual as well saves a lot of time figureing what goes were.
Regards
John
PS or a box of matches which ever is cheaper

G'day StayyerAU,

This is a somewhat common problem with 1HZ's apparently

Have a look at this thread on the "4wd Action website. You may need to register if you're not a member but it's well worth being one.


http://www.4wdaction.com.au/forum/viewtopic.php?f=76&t=99139&hilit=75+series+overheating

Robert

Hi Stayer
Toyota had recall on cruisers (mine a 2003 wagon) a problem with wireing around the fire wall as said above, contact Toyota worth checking.
cheers
Lee

Gday


Thanks for all the excellent information, and thanks for the 4wd action link Goldnomad, after a brief read I can see that many others have had similar issues with their cooling systems as I have had in the past, that part of it seems to be sorted out but the wiring thing with the gauges might be a mission.

Still think its a short or bad earth in the wiring system, one thing I know with vehicle overheating issues is that they dont suddenly overheat and cool down in seconds, once they are really hot they stay hot for quite a while,and for the temp gauge to go to its limit that would mean that the engine was boiling, when I stopped the engine was not too hot that you couldnt lay your hand on it and the radiator wasnt bubbling, the temperature seemed to be normal.

Freshwater I have had a brief look at the wiring but found nothing obvious as yet, it wasnt wet the day this happened and it has not happened again since, intermittent electrical faults are really hard to find so I always try and duplicate the problem, like while the engine is running at normal temp I will get someone to sit in the car and watch the gauges while I move the wiring harness and connections to see if there is a sudden change, sometimes you are lucky and by accident you can make it happen and therefor pinpoint the area that is at fault.

Hopefully it will be that easy, but I doubt it though somehow,the problem with these sorts of issues is that you tend to forget about them when they dont happen all the time, and that can be a trap because the next time it happens and it could be worse as it might be in the scrub and miles from home, either way I need to get on to it and find the fault.

cheers

stayyerAU

TO BE SURE --CHANGE THE THERMOSTAT--

regards
oneday69

stayyerAU, im not familiar with your model vehicle so this may not apply. On many latter models, and not so latter, they use a regulator behind the instrument cluster to regulate 7-10v. My 97 rodeo has this as it uses an electronic speedo, and not a cable one.
If its faulty it would do just as you have described. A crack in the maylar near the solder, or a dry solder could cause this.
The maylar contacts where they meet the wiring plug may also be cracked or dry solders on the pins that connect the two together.
Maybe worth a look if yours is of this nature.????

My Nissan did the same thing. Was all related to a poor earth from the battery. Temp gauge went up, turned on headlights, temp gauge went down.

Rang my brother, an auto sparky... his comment... "Tighten your battery earth"

Did that... all good ever since.

oneday69 wrote:TO BE SURE --CHANGE THE THERMOSTAT--

regards
oneday69

Gday

That was the first thing I did thinking that the thermostat might be sticking, even after testing the old one that was clean and still working ok, changed it anyway, then later replaced the water pump as well in case it was fluctuating water pressure.

cheers

stayyerAU

Narrawa wrote:stayyerAU, im not familiar with your model vehicle so this may not apply. On many latter models, and not so latter, they use a regulator behind the instrument cluster to regulate 7-10v. My 97 rodeo has this as it uses an electronic speedo, and not a cable one.
If its faulty it would do just as you have described. A crack in the maylar near the solder, or a dry solder could cause this.
The maylar contacts where they meet the wiring plug may also be cracked or dry solders on the pins that connect the two together.
Maybe worth a look if yours is of this nature.????

Gday Narrawa

I get what you are saying and think that myself, either some kind of regulator or even a contact on one of the plugs, the problem is spasmodic and only happens from time to time, I know its not an overheating problem as I have covered all those bases already, the issue seems to be relative to both the temperature gauge and also the front fuel tank gauge that are both behind the same clear panel as the speedo.

I have removed this all before, cant remember why exactly now and its a big job, so I will be doing it soon as I am not going bush for awhile now, the steering wheel and several other mounted accessories all have to come off to get in there, and there are some other things I want to do in the front of the car so I though I may as well do it all at the same time.

cheers

stayyerAU

StayyerAu, im hearing ya, iv been chasing a crook fuel gauge problem with my rodeo for the last two years now.
Iv had the dash out cleaned and checked, and replaced the sender in the tank twice with second hand units after checking all parts of the cluster were in check. All wiring to and from all in check.
No luck up until about two weeks ago when i pulled the sender out again for a final blow.
The wiper on the sender operates in fuel, diesel fuel that can develop an algae. I took it apart and gave the wire loop the wiper works on a rub with light sand paper, then bent the wiper shaft to give it some more pressure on the wire the wiper runs along as the float go's up and down with the fuel lever and what do you know.???
Problem fixed.
Hope you find it soon as these things tend to play on your mind.