ib516

So, at what temp does the idiot light come on at?

I heard in the 2nd gens, it was 270 - 280*F, but don't know if that's correct.

OOPS

I have had mine at 270 and the light did not come on.

2007 5.9

Supposed to come on at 280*....supposed too!!!

donnee

That is if everything is working as it should.
Usually by the time the idiot light comes on its too late.
JMHO.
Thats why I put a gauge in for the necessary items.
I dont trust the lights.

TexasCTD

Why would they set it for 280 if that is already to late?? Why not set it for 230 or 240??


Probably for the same silly reason they go to the trouble to install an oil pressure gauge in our trucks that doesn't actually read the oil pressure. It is just a dummy gauge that tells you what DC wants you to know.

..

no_6_oh_no

Factory temp sensor is supposed to trigger a light at 260 degrees. In reality it could be 20 degrees either side of that depending on the sensor and how the ECU and cluster module is reading the signal. It is notoriously unreliable.

Even 280 degrees is not enough to hurt the fluid or trans if it is not a frequent occurence. The light is more of a fail safe to notify things are getting out of hand and one needs to figure out why.

RowJ

Factory Service Manual says warning light & chime come on at 135*C/275*F, on 2nd Gens.

I believe the 48RE sensor in the 3rd Gen is the same but....don't have that manual.

I agree with 'No 6...' . It's an alert that something may be wrong and you should keep an eye on it.
It's better than not having one....No? 275*F is not going to cause tranny failure but still way too hot for continuous operation. Just about right, IMO.

RJ

CamperAndy

Your old school with 30 year old oil if you really worry at 230 or 240. Since new just tooling around town I can hit those numbers. Once I lock up the temps drop to 160-180.

As for the oil pressure gauge why do you say it is a dummy? Are failed engines in the best interest of DC?? If the gauge is wrong and you wreck your engine due to low pressure do you think they will not repair it by saying you ran with low pressure even if the gauge says it is okay??

ib516

Thanks guys, BTW, mine HASN'T come on. Just wondered how bad it will be if it ever does light up. I doubt it, since my RV is 34' travel trailer, and weighs in around 9300# or so.

TexasCTD

I was being somewhat sarcastic in my comments in my first post in this thread. I have a trans temp gauge and have never seen my fluid go over 220, towing or otherwise....and I have never seen the factory light come on. The 3rd poster said that it was supposed to come on at 280. I just feel if they were going to bother putting the light in....it should come on sooner than that. I think 280 is to high for the warning........particularly since the sensors are unreliable like no 6 oh said.


Regarding the oil pressure....it is a dummy gauge. Im serious. That is not a joke. I don't have documentation to back that claim up, but I have read it numerous times right here on DTR. The gauge reads in a particular zone set by DC after oil pressure reaches some somewhat lower number. If my oil pressure did drop I know it wouldn't be warrantied since my truck is bombed...and about to exceed 100K miles anyway. My point was, if they are going to the trouble to put it in...make it useful and accurate.

..

Scottygl62

I tend to agree. I have a mechanical oil gauge and it will read from 24 to 75 depending upon engine RPM's, whereas the dash gauge will stay between 40 and maybe 45.

coparam4x4

I think DC makes their oil pressure gauge read the way it does so that people dont freak out about the drop and rise in oil pressure due to rpm's. I used to have a Titan and the oil pressure gauge actually worked, it would rise and fall due to rpm's. I cant tell you how many threads on the Titan forum there were on people freaking out about how much fluctuation there was in the oil pressure. Everybody thought there engine was going south...JMO

RowJ

Just what I always suspected...without your "Titan" evidence to back up my assumption.

I would not call the Dodge oil pressure gauge a "dummy"! It's simply designed to read three basic parameters.
1- Too much pressure and 2- too little pressure.... It does an excellent job, IMO, on these two.
The third parameter is to fluctuate a little up, with more rpm, and a little down, with less rpm, basically staying in mid range, if pressure is as it should be.

Before the newer pressure sensor in 02, owners complained they could not trust the gauge because the needle just sat there in the middle and never moved. So Dodge made it move a little with variations in rpm......... but not enough for worry warts to "freak out"!
I'm guessing here but I suspect they also had to guard against old school racers that still insist on 10 psi pressure for every 1,000 rpm... at all times.
With the pretty much perfect oiling system on the Cummins, the need for a more accurate pressure gauge is of no concern to me!

RJ

N.Johnson

From the shop manual

Trans Over-Temp Lamp-On Message - Each
time the cluster receives a trans over-temp lamp-on
message from the PCM indicating that the transmission
fluid temperature is 135° C (275° F) or higher,
the indicator will be illuminated and a single chime
tone is sounded.


The oil pressure gauge gives an indication to the
vehicle operator of the engine oil pressure. This
gauge is controlled by the instrument cluster circuit
board based upon cluster programming and electronic
messages received by the cluster from the Engine Control Module
(ECM) on vehicles equipped with a diesel engine over
the Programmable Communications Interface (PCI)
data bus The instrument
cluster circuitry restricts the oil pressure gauge
needle operation in order to provide readings that
are consistent with customer expectations. Each time
the cluster receives a message from the PCM or ECM
indicating the engine oil pressure is above about 41
kPa (6 psi) the cluster holds the gauge needle at a
point near the middle increment within the normal
range on the gauge scale.