This is long… Read at your own risk.

Subject: Linear Logic Scan Gauge II / X-Gauge Engine Coolant Temperatures on Automatic Transmission Equipped Vehicles and Display on the X-Gauge. Read no further if your not affected.

Up front: Why do I get caught up in having to know an answer no one can give me! Six months and several headaches I have the answer and the people who designed it telling me the how and why.

The Process: I started this process in February of this year following a thread post and some, well, harsh comments.

After seven emails and as many phone conversations with Linear Logic concerning the Scan Gauge II / X-Gauge Engine Coolant Temperatures Display and most importantly “how they get them when the sensor as it not reporting to the PCM,.

The Question and comments have been overwhelming in the internet and other forums.

For whatever reason, I thought let’s call Ford. So, I did I explained I was a past employee of 15 years and the issue I was having because of the wiring to the gauge and not the PCM on Automatic Equipped Ford F-250-SD 7.3L DIT Vehicles.

I further explained I had the latest IDS and other tools which do display the PID’s but others like mentioned here in the forum do not and some have difficulty trusting other Scan Tools..

His response was “1999” I said yes. He said he would have to look that up and get back with me. So, only a couple business days from last Thursday I get his email explaining how the PID is displayed on the IDS. Its posted below as a JPEG.

And finally it makes “some sense” as it’s being fed by a Key on Hot at All Times Circuit which has its voltage reduced as it travels through the sensor. The circuits are monitored by the PCM using variables of “how much it’s pushing through the circuit” on the Supply Side Voltage. Why? because anything over 8,500 lbs. was not required to be monitored by the PCM and with a 104 in/out data ports they were at a premium. ECT didn't make it, per-se.

I have to admit, I am not an engineer. This all made my head hurt. But Ford has had, and for the foreseeable future, a Water Temperature Gauge on the Dash Cluster for the operator.

I have been after this answer for years. But, using only the Wiring Diagram was not what I should have been focused on. That coupled with some code, Multiplication / Division / and +/- Specifics to adjust everything gets one within say 5*F as I personally checked the IDS and my Scan gauge / X-Gauge with an OBD-II Slitter and used an IR Thermometer as well as Thermometer in the Degas Bottle.

The only thing I, nor Linear Logic could explain was why there gauge reads 250 *F from start to warm engine at 140*F (Ford Engineering said the have a line in their code in the IDS which calculates its values +/- based on testing)

They [Linear Logic] were nice enough put up with the emails, calls, etc., Kudo's to them over the past six months. And were nice enough to provide all their data points and values to use as comparison for calculations but none were as accurate as the one I found on the Internet years ago:

TXD: C410F1221139
RXF: 046205110639
RXD: 3008
MTH: 00010002007F

When I used the ones Linear Logic sent I saw temperatures at 255*F in my stall. That’s when I hooked everything up to see what was what in the previous paragraph! Scared me as my EOT was at 194 and the Probes were at 185*F.

I also found out from Ford the highest recommended ECT for the 7.3L DIT was 250*F although the FOMOCO Service Manual references 240*F.

Of course this is based on a maintained cooling system with proper coolant and change intervals and SCA added to Serviceable Levels.


Redacted e-mail:



Every PID which I was able to compare and was within 5% of the IDS. I used the IDS as the standard since there were millions invested in the system for the next generation tool. Disregard the maximum temperatures as I'm supposed to get another email updating the Factory Service Manual which was published but I do not have that addendum written in 2002.






I was directed to this Open Source OBD-II Information for our Model Years.

 

Well, shoot. I coulda told you that!



I read a lot of your posts with lots of info in them. It takes a while, but I usually go through them fully. Always learning. Thanks!

 

I'm trying to work out how Torque Pro has an IPR address of 221434 vs. all the codes for IPR for the Scan Gauge II. They don't translate to/from hex.

See? I am paying attention.

 

IF I understand Ford, TXD: [C410F1231310] Address in the OBD-II System. Like an IP Address? This is where it is attempting to acquire the data like being transferred to a computer via a switch or router.

RXF: 04624513061 This is actually the data retrieved through a " VPN Like tunnel", that being #1139 in this instance.

The MTH is where the magic happens.

MTH: [0009] [0005] [F060]
Multiply - Divide- +/- for accuracy

In this case, the data is multiplied X 9, then Divided by 5, An "F" for Fahrenheit Display (Guess!) on Gauge, and lastly 060 is the fine tuning of the value +/- which I don't have a grasp on as yet.

But, I know if you change any part of the MTH the Screen Value changes. If the first two (TFD or RFX) are not correct, nothing will display.

There are several sites which explain the OBD-II Open Source Software which I was unaware of. I thought it to be proprietary. But, GM lost the case in 1982 and it was ruled Open Source because of the government mandate.

Do a Google and maybe you can find your answer - Good Luck.

 

Just a toss in the dark, but TX & RX usually means Transmit and Receive, Those designators might be Data Buss addresses.....Just thinkin.....

 

Okay, so, after getting my updated manual for our trucks that, apparently many did not get with their subscriptions, I have re done the Temperatures and Suggestions stated therein.

**** This affects vehicles WITH ENGINE BUILD NUMBERS GREATER THAN #940613 .... ******* Navistar had a running change for implementation of improvement to the DIT introduction. NOT the "99.5 Model alone".

INFORMATION OBTAINED:

***The latest flash is #DPC-422 PCM which added Horse Power, Defuel, Corrected some issues and addressed customer concerns which were many. Shifting Issues with the Auto Transmission and some feed back sensors reporting erroneously. Also, Transmissions with PTO Applications were an issue. An engine seal and heat dissipation process based on Customer Concerns via Dealership Reporting. ***

My take on this. I flash a lot of vehicles both Gassers and Diesel. What I find is the Customer either loves it or hates it.

So, I explain to him/her the process, the charge which is non refundable by Ford and the Labor involved. Sometimes they wish to try it, others refuse it.

To each their own. I don't blame either.

You can always go back. BUT, there is still a cost!

*Note the Glow Plug is ON / OFF not % of use. 99=ON / 0=OFF

* See the note about towing heavy and some chip manufactures. I'm not saying it's a bad idea to use your chip, just that an additional strategy was employed in this build number to reduce EGT's. If your Truck has been flashed regardless of year, it now has the newer strategy. I am awaiting date implementation and Flash Reference Number for the Rep.

Also note the Take a break part which is verbatim from the FSM Update. The vehicle should be pulled to the side of the roadway and allowed to idle up to 1,000 RPM;s until return to normal. Then you can repeat the process as necessary to complete your trip. Interesting.

 

I hear ya!

I've been to numerous classes and have a bunch of paper that says" I know what I'm talking about..... BS!"

I am lost here and have been to the Master Tech Class for the IDS! Hell, I did pretty good! But, I'm lost now that I found how they generate information! I won't let this go. My Kids... Yes, they can go, not this.

 

Your Ford contact's info confuses me a bit. On the manual transmission trucks, the ECT sensor feeds the dash gauge identically to an auto tranny truck. There is a SECOND ECT sensor that feeds the PCM, and it feeds the same PCM inputs as the tranny temp sensor for an auto truck.

Further, he says that the ECT input on a manual truck is used to control the high RPM for warmup. I don't think that's true. I rigged a potentiometer in place of the OIL temp sensor, and using a plot of known resistance values to EOT, I could fool the PCM into thinking the oil temp was whatever value I wanted. This exercise directly affected RPM.

Is any of this important to you guys? Probably not. I've been on the longtime quest to resolve excessive cold start smoke, though all the usual suspects have been thoroughly tested. Along with that, there's a strong contingent of guys with manual tranny trucks who experience this plague. I honed in on the fact that manual trucks have the second ECT sensor, feeding the same PCM inputs as the auto tranny temp sensor, which, according to Ford, is used to restrict both fueling and shift points when the engine is cold.

I'd like to hear the Ford fellow's ideas on this matter, if he cared to comment. I have a new replacement for the second ECT sensor, but have procrastinated on swapping it.

 

this is fascinating

 

Very good info! Keep up the "headache" good work.

 

I can dig deeper after my brain takes a hiatus. This will be the first 72 consecutive hours of no work, or online support at work since.... Since.... Uh... New Years.

 

Regardless of why you all do this, just know there are lots of us who really appreciate all that you do for the community!!

 

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