Virtual temp gauge -yes or no?

[Matt400]

I was reading up the other night and came across a bulletin for 05 Jeep CRD's

Seems owners may complain of higher than normal temp readings especially in hot ambient, uphill or towing conditions.



Not a problem, just swing in to the Dealer and get your cluster re flashed with new software that will keep the needle at a more "customer preferred" setting.



So now this gets me to thinking and reading the Rams OEM manual. I find the Rams set up is the same as the Jeeps as far as how it arrives at the needle position but did get a partial relief reading this statement-

"The needle is moved to the actual relative temperature" of course this is based on the sensors input to the ECM and the clusters interpretation of the ECM's output to it based on its programming. Makes you wonder...



So does the statement in bold make it real, or does all this sound virtual?

 

[jwduke]

All sounds virtual, if you don't like the gauge reading your D/C vehicle has, take it to the dealer, and we will make it read what you think it should read.



Kinda like the oil pressure gauge, our trucks have.

 

[klenger]

... or reflashing the ECM to make the overhead computer read higher milage.

 

[rbattelle]

I believe it's real, and I have proof. I have an OBD-II system operating whenever I drive my truck which, among other things, gives me a digital readout of engine coolant temperature. It agrees with the factory gauge (although the factory gauge actually lags behind the true temperature a little bit... . maybe 30 seconds to a minute).



-Ryan

 

[Cattletrkr]

I voted "Real" based on what my Juice/Attitude shows. However, I get the funny feeling it's just a different visual for the same crappy data. I'm thinking I should have voted "dunno".

 

[Matt400]

I voted "Real" based on what my Juice/Attitude shows. However, I get the funny feeling it's just a different visual for the same crappy data. I'm thinking I should have voted "dunno".

Maybe I should have added a 4th selection- "Real data/Computer Enhanced" :-laf :-laf



The data in the ECM is important for diagnostics so I tend to agree that the temps at that level are real. However as that data is sent to the cluster the software in the cluster obviously has the ability to modify this data based on the CRD bulletin and the OEM manual, so for those owners that have had the flash I ask- was the temp gauge real before or after the flash? :-laf



I just had a thought! Its real with the added feature for recalibration to a preferred setting :-laf :-laf Im voting #3!

 

[Cattletrkr]

The data in the ECM is important for diagnostics so I tend to agree that the temps at that level are real.

I would guess that's where the Attitude gets its numbers from. Since the attitude and the dash gauge read the same, I guess I'm sticking with "Real".

 

[jimnance]

If I recall correctly, the thermostat for the '05 CTD is 190F or 195F. Mine moves smoothly from within a couple of degrees of ambient at start up in the morning on the attitude to run 190-195F once fully warm. I vote for real because the attitude readout agrees with what I would expect to see.

 

[brods]

Finally got the 05 service manual and here is what it says:

The EMIC microprocessor smooths the input data using algorithms to provide gauge readings that are accurate,

stable and responsive to operating conditions. These algorithms are designed to provide gauge readings during

normal operation that are consistent with customer expectations. However, when abnormal conditions exist such as

high coolant temperature, the algorithm can drive the gauge pointer to an extreme position and the microprocessor

can sound a chime through the on-board audible tone transducer to provide distinct visual and audible indications of

a problem to the vehicle operator.

Sure sounds fake to me, at least for the 05s! One of the most important aspects of gauges, imho, is getting real time data. When something doesn’t seem right I look at the gauges and if what they show me is not an accurate picture of what is happening at that very second, then the information they give has no value as a diagnostic tool and even worse could allow me to continue running the engine for a longer time until the software lets the gauge catch up. Without knowing how much the software tweaks the output (dampening or outright fabrication) it becomes just another fancy idiot light!



Someone please tell me that at least the tach is real and not tweaked to be "consistent with customer expectations"

 

[CArnold]

This is what the service manual tells us. .

On vehicles with a diesel engine, the ECM continually monitors the engine coolant temperature sensor to determine the engine operating temperature. The PCM or ECM then sends the proper engine coolant temperature messages to the instrument cluster.

 

[VTomasso]

Hi All,



Just thought I'd throw this in... I recently got around to installing my Jacobs E-Brake on my 04. 5. According to the installation manual, the warmup feature is supposed to disable above about 170 F. I've noticed that even with my temp gauge right at 200 F, the brake still stays on at idle. If I continue to run the truck for a longer period, say 30 minutes or more at 65 F ambient, the brake will disengage at idle like it's supposed to.



Kind of makes me wonder what my coolant temp really is



I'm inclined to believe that the ECM command temp for the brake is the accurate one.

 

[sag2]

I spent a lot of time on the 03 and 04 with the DRBIII and I can say for those two trucks the gauge was within a couple of degrees of the coolant temp sensor. When I get the 06 I'll check it also just to see.