Cat 426 Oil light + Horn + Neutralised Transmission

[Snobdds]

Thanks,
The oil pressure transmitter/gauge is aftermarket and was validated when installed with a mechanical gauge. I know of no oil-level sensing as such on the engine. I presume it's the original oil-pressure switch that trips the oil-pressure red light and the horn. I had this before momentarily with extreme nose-up attitudes a couple of times but NEVER with a concurrent transmission cutout. The problem is I cannot find the Pr-Sw or its pigtail, some books show it on the oil-filter adapter but mine has nothing there.

if you mean the oil-pr-switch I can't find it, nor the wire going to it

I'm confused.

 

[fitterski]

I think OP has an oil gauge, so he knows what the pressure is. He can't find an engine oil pressure switch that is suspected to be triggering alarms.

Spitballing here, but:
...why would the engine oil pressure switch initiate a transmission cut-out? Are you sure "oil light" is "engine oil light" and not something else ("tranny" or hydraulic oil)?

Isn't a Cat 426 a geared tractor?
What does OP mean by it stops moving? Does engine keep running when light and horn go on? How does it neutralize a gear transmission?

the 426 is geared with a torque converter as I understand it (i'm no mechanic really)

the 416 operator manual p14 calls the light an "engine low oil pressure" light (don't have 426 op manual)

i put it in gear and rock nice and slowly with the fore/aft lever watching reaction speed

engine keeps running all the time

I'm no longer thinking of 'neutralizing' per-se, can't edit the subject header, having once disconnected the neutralizing solenoid changed nothing

Just fishing, I disconnected the reverse warning switch on the tranny. That resulted in a horn while the fwd/rev lever was in neutral, horn silenced in fwd or in rev while reactuion still degraded over time. Reconnected the switch, everything same as before.

As before, I notice that engagement speed deteriorates with passing minutes, need to give more and more gas to get rolling. In this condition I'm not sure I'd want to try a stall test, it doesn't really seem like a solenoid neutralization which would be on of off.

 

[LeglessCrow]

Just because you can’t find the oil pressure sensor doesn’t mean it’s not there. Every engine has an oil pressure sensor. A one cylinder ya mar even has an oil pressure sensor. Given your symptoms it sounds like that’s your problem. I understand you’re not a mechanic but you can’t just decide your problem is way more complicated than it is simply because you can’t find the sensor. Find the sensor and make 100% sure it’s functioning correctly before moving on to other things. Keep it simple. Having three different unrelated problems happen at the exact same time is extremely unlikely. Especially when all of those problems are exactly what an engine does when it thinks it doesn’t have any oil in it to protect itself.

 

[radios1]

have you checked the transmission fluid?. also, if the tractor has a computer, it may have whacked out!.

 

[fitterski]

Re: Cat 426 Oil light, Horn, Immobilizing

Just because you can稚 find the oil pressure sensor doesn稚 mean it痴 not there. Every engine has an oil pressure sensor. A one cylinder ya mar even has an oil pressure sensor. Given your symptoms it sounds like that痴 your problem. I understand you?*e not a mechanic but you can稚 just decide your problem is way more complicated than it is simply because you can稚 find the sensor. Find the sensor and make 100% sure it痴 functioning correctly before moving on to other things. Keep it simple. Having three different unrelated problems happen at the exact same time is extremely unlikely. Especially when all of those problems are exactly what an engine does when it thinks it doesn稚 have any oil in it to protect itself.

I certainly intend to find it if it's there or to know for sure that it isn't if it isn't Just made myself a simplified wiring diagram to help with the TS, though the real wiring isn't exactly the same. It's a 32 year old rig so the wiring isn't in too recognizable a condition in places. The issue of lettering on the diagram connectors BTW means the harness names. One of 3 coolant sensors seems to share the D harness that I need to find, I'll try to backtrace from the engine bay, the E harness from the dash is mostly in a door pillar impossible to follow (to it). I might get on that this afternoon or tomorrow.



No computer on machine (the Lord be thanked!)

 

[fitterski]

have you checked the transmission fluid?. also, if the tractor has a computer, it may have whacked out!.

have you checked the transmission fluid?. also, if the tractor has a computer, it may have whacked out!.

you was close!

Resolved!

The last pro who has been working on the machine for 10 years also installed the pressure gauge and had then decided to MOVE the presure-switch to the tranny filter. The horn went off a little late each time to be an 'alert' when a dirty strainer caused a self-induced vacuum leak. The strainer was last replaced in 2006 by the former pro who now has the ball again. I'm not equipped to do anything on trannies so I didn't even try.

Thanks for the hunches and comments!!!

 

[crashz]

The tranny fluid will get pretty gross in those after a few years. We always changed the filters annually and fluid every few thousand hours on my father's 416 and wheel loaders. After dropping $25k on a tranny rebuild in his Cat 950, we paid a lot more attention to the transmissions after that.

BTW the Cat fluid and filters are the the best options and surprisingly reasonable.