1hdt Oil Sender Unit issue(s)

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Hey there!

Having an issue with my 80 series. I've recently changed the oil sender unit and now my dash is light up. T.Belt light, low oil pressure light, water in fuel filter light. Also am not getting a good oil pressure read on the dash. I've tried resetting the T.Belt lamp, but that didn't work. Also I changed the oil sender back to the old one. Still is doing the same thing. I'm wondering if anyone knows of a wire harness around the area of the oil sender in the side of the block near the oil filter which could control the dash board lights???

Thank you for all the help.
 

jellis

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Agreed, something else was tweaked electrically. The "christmas tree" dash light phenomenon is well documented on here.

Did you swap the alternator to a new one at the same time perhaps? I swapped out my dash lights for LEDs and now they all stay lit up after starting until my alternator outputs 12.8V at which point they all switch off like clockwork.

Could be a bad ground somewhere? Check the wiring diagram and start diagnosing with an ohmmeter.
 

ToyotaMatt

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IS this your set up by chance ?

a double sender and switch too system ?

if so i can help ?

thanks matt



OilSenderAndSwitch (1)1.jpg
 
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Hey guys, going to chase it some more today. I'll look up the "Christmas tree" phenomenon on here also. The alternator hasn't been messed with at all. It's starts up everytime and stays charged. While doing the oil sender I did change the fuel filter also. Appreciate the reach outs
 

ToyotaMatt

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oh i got it now ,


- you have hooked up your round button connector and the secondary ground tab lead on the mechanical sending unit backwards , and in-turn full fielded your oil gauge

in the cluster meter itself , which in-turn fried your cluster meter circuit board itself creating the X-MASS tree effect........



i run into this all the time in the 80 series forum from folks with a 1FZ-FE ,


look into my theory above and report back with several good clear TECH images too


kindly
matt
 
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oh i got it now ,


- you have hooked up your round button connector and the secondary ground tab lead on the mechanical sending unit backwards , and in-turn full fielded your oil gauge

in the cluster meter itself , which in-turn fried your cluster meter circuit board itself creating the X-MASS tree effect........



i run into this all the time in the 80 series forum from folks with a 1FZ-FE ,


look into my theory above and report back with several good clear TECH images too


kindly
matt


My thoughts exactly
 
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I eventually had to disconnect the alternator warning light wire to get rid of the xmas tree effect. Not the case here, but FYI.
 
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Alright guys, sorry it took so long. Life got busy. Anyways, I took my time and really looked at the connection wires. Found the main power wire worn and cut from old age. I spliced and replaced and reconnected. I now how power to the oil sender and the gauge just takes it above H when the ignition is turned on. But I still have the boost lights, water in fuel, t belt, and oil pressure light on.

Any ideas on if it's a wire harness issue? All of this worked basically a week ago before I changed out the old sender. Would ordering a new oil sender work? Tomorrow I'll disconnect the alternator warning light wire.

thanks foe the help
 

mudgudgeon

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The random dash lights is often due to a bad connection at the alternator, bad ground from the alternator, or bad alternator itself.

The hdj80 have a problem with the wiring going to the back of the alternator being a bit short where it passes from the body, to the alternator and engine movement tugs at the wiring which can break wires
 
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Alright guys, sorry it took so long. Life got busy. Anyways, I took my time and really looked at the connection wires. Found the main power wire worn and cut from old age. I spliced and replaced and reconnected. I now how power to the oil sender and the gauge just takes it above H when the ignition is turned on. But I still have the boost lights, water in fuel, t belt, and oil pressure light on.

Any ideas on if it's a wire harness issue? All of this worked basically a week ago before I changed out the old sender. Would ordering a new oil sender work? Tomorrow I'll disconnect the alternator warning light wire.

thanks foe the help


The gauge going above H when you turn it on means it's been shorted out and is damaged. you grounded out something in the dash when you incorrectly hooked up that gauge and you're going to have to probably replace a portion of your dash like Matt previously said
 

ToyotaMatt

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i hand-krafted this oil sending unit SUB-HARNESS Section , technically called " ENGINE WIRE No. 4 " on the microfiche for another Diesel TECH. / 24V Fellow member a

few years ago , he had the EXACT issue and symptoms you have going on except this part also melted in place pretty severely as i recall , hence the need for a replacement


NOTE : this was for a 12H-T application , and for example TECH study only here and reference etc ........





SEE LINK BELOW :








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