FJ62 Oil Pressure Gauge

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RJC409

RJC409

Joined
Dec 30, 2015
Threads
7
Messages
45
Location
Loveland, CO
I need some help problem solving my oil pressure gauge. let me say first, that I do not want to put a mechanical gauge in the system. My 62 is all original and everything works perfectly except the oil pressure gauge and I don't want to add an auxiliary gauge to the system. The original system worked and should be made to work again.

I've replaced the sending unit and have tested the gauge by placing a 12v bulb (resistance) between ground and the gauge lead (black and yellow wire). The gauge needle starts climbing although ever so slowly.

The problem is I can not find any detailed info to problem solve. Does any one know what the voltage should be coming from the gauge lead? Mine measures system voltage (~13+ volts). I would think the voltage would be less since it passes through the gauge. If I new what the voltages and resistance of the gauge and sending unit should be I can determine where the problem lies. Though I believe the problem is the gauge I would like to verify it. The fact that I can make the gauge needle move by putting resistance in the circuit makes me hesitate to replace the gauge.

After replacing the sending unit, I measured the resistance while the engine was running and the resistance is roughly 45 ohms. Seems right but again, I don't know if this is correct either. I tested the oil pressure and I have good oil pressure.

Help Please.
 
On a 60, I don't know if this is the same on a 62, if the wire is connected to wrong post on the oil sending unit, it fries the oil pressure gauge!

As I recall, the wire connects to the small pin, not the spade pin. If this is wrong, I'm sure someone will chime in with the correct info.

Was the gauge working before the sending unit change?
 
If it's any consolation...
Oil pressure gauges on the cruiser IMO do more harm than good. They are rarely accurate and people fret over them to no end.
The oil pump is the most reliable, dependable, long lasting, heavy duty, simple component on the engine. And its submerged in oil. They don't wear out.

I've have never once read a thread here on mud (& I've read a lot of them) where someone noticed low oil pressure on the gauge, then took corrective action which then prevented damage to the engine. Not once.
Many engines are not even equipped with oil pressure gauges.

IMO, a dead oil pressure gauge is only an aesthetic setback. A working one is not going to help you prevent anything. It's more of a distraction than anything.

But after saying all that, I'd want my oil pressure gauge working too if it died. I don't like looking at dead needles either.
 
Thanks for the inputs.

Yes, my motivation is purely aesthetics and principle, I want the thing working like it is suppose to. My 62 is one of the nicest I've seen. I am trying to sell it and this is the only item not working. Driving me crazy trying to figure it out. Again, I'm pretty sure it is the gauge just want to be sure before investing the $ and energy into a new one.

Doug72,
I bought this truck with a blown head gasket and replaced the engine. The gauge has never worked and I do have it connected correctly. Not to say that the previous owner hooked it up wrong at some point and fried the gauge. I had already looked into this possibility and removed the gauge and inspected it. It looks perfect and the fact that I could get the gauge to function make me hesitate to assume it's bad but everything else seems to function correctly.
 
I just swapped motors petrol to diesel, oil pressure gauge worked fine, temp didn't move. When I tried again after plugging in fuel sender, the oil was way high (with engine off) temp was 1/4, what would cause this? Have been putting dash in and out while working out diesel tacho (that works now)
 
I also accidentally cooked my oil pressure gauge by hooking it up to the wrong terminal (why Toyota, why!?)

I found out however that the gauge was not dead. I noticed that after the cooking, the needle sat way below the lowest tick-mark on the gauge. It was almost past the "L". I was able to open the gauge up and carefully bend the mechanism so the needle rested on the lowest tick-mark like it did originally. After that, the gauge returned to normal operation (once I hooked the sender up correctly).

My assumption is that the gauge got so hot, that it over-traveled and bent the mechanism.
 
Last edited:
Hey guys, I had this problem created when I was replacing the sender unit. I was in the process of expanding the oil data information by adding an advanced capability. I "designed" the process, then gave it and the parts to my local shop to do the labor. They accidently used the "obvious" connection...which fried the OEM gauge. I say fried, but...I had several solution paths. I did dig up a used one, but like @Lead Head, I carefully bent the needle back to the proper starting location. The new one went in, and I have the original as a backup.

OP, I see you don't want to go outside of original. I'm kind of the same way, so when I did my expansion of oil data, I went with an easily removed under dash mount of two gauges: oil pressure and auto tranny temp gauge. What I added was a low oil pressure alarm (5psi sender and little alarm blaster). Of course there is not OEM tranny temp gauge, and with heat a significant design problem, this became another mission. You can check out these at link below. There are two short videos demonstrating the low oil pressure alarm. I think if you just continure reading from that post, it covers the things I did to overcome the hot tranny problems.

FWIW...Build - Sentimental Restoration of Family 1990 FJ62 - https://forum.ih8mud.com/threads/sentimental-restoration-of-family-1990-fj62.1095049/page-10#post-14126142
 
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