My old 1999 F250 SD (7.3l TDI) just recently suffered the infamous clogged strainers in the fuel tank problem, then later the inline fuel pump (the one on the frame rail under driver's side) failed. I've dealt with all of that, removed the strainers, installed an inline filter ahead of the supply pump, new (NAPA => CARTER) supply pump, yadda yadda...

Everything seems fine now, and starts/runs like brand new (actually, it starts better than ever before), builds and maintains fuel pressure that appears to hold solid even under max load.

I have been logging runtime data using DashCommand on an android phone, and a cheap ELM327 OBD module...

I noticed that the 'FORD.ENGINE.ECT' PID will show temperature readings only after the temperature gauge on the instrument cluster (the one on the truck, not the one on my phone), is up to normal range. As time passes, and the PID data indicates a temp of 250+ degrees F, it suddenly goes to some negative value. Once the temp falls below 250 F, Dash Command gauge starts indicating again...

(ok, sorry for all of that. now for the question...)
Anyone happen to know what's causing this behavior? The truck seems to run fine, and the temp guage in the truck never goes high or low of mid range until I've shut it down. Are there more than one coolant temp sensors on the early 99's?

Mine was made in 98 for the Canadian market, if that makes a difference...then later 'imported' into the US where I purchased it used...

As far as I know, the ECM is original to the truck. I'm second owner, but have had it since about year 2000 when it still had around 11K miles...

Thanks,
-Vern (aka Brutus Jr)

p.s., I also installed a cheap-o stuart-warner electric oil pressure gauge (0-100 psi) in the fuel system. Best thing I ever did! The gauge is mounted in the dash, and the sending unit is plumped into one of the ports in the filter bowl. Cost was ~$30! It helped me identify the problem when my OEM supply pump was dying/died...

 

The PCM doesn't monitor coolant temperature on 7.3 trucks with automatic transmissions.

 

I'm not disagreeing with you here , it's just that this is confusing...if that's true, and the ECU isn't reporting coolant temp, then what is my ECU reporting as the ford.engine.ect? In my case, the data clearly responds to engine load (i.e., goes up faster with increased load, and falls with decreasing load...). This isn't of huge concern, as I said the truck seems to run fine. But this data sorta has me scratching my head... ...and yes, my truck does have the automatic transmission...

 

btw, I did find a [very] similar question in another forum (see: https://www.scantool.net/forum/index...ic=3470.0;wap2), which apparently was answered by someone from PPE. But the link they provided no longer appears to be valid.

 

Pikachu is correct. I have the wiring diagrams for our trucks - the coolant temperature sender is wired directly to the gauge on the dash. Do not pass PCM, do not collect $200. Without a direct connection to the PCM or some other module, there is no possible way for that information to "leap" to the OBDII port - for you to monitor. The ECT PID is for manual trucks (which uses a different part number for the coolant temperature sender), but Ford put some kind of test thing in place of that PID for automatics.

I've logged that phantom PID more than once, and it's a confusing bugger. Maybe I'll decode it some day... but I do have insight on some of what it's doing. That's an experiment for another time, though.

All these years of driving gassers, we are brainwashed to thing the ECT is the big thing to watch. What we really want to watch on a turbodiesel is Engine Oil Temperature, Exhaust Gas Temperatures (both of them), and Transmission Fluid Temperatures. The ECT is close enough to EOT (usually within 10 degrees), that you can roll with EOT.






Oh... and you're missing out with Dash Command. You likely want Torque Pro.

 

The ECT (Circuit #37 / PCM Pin) does report to the PCM. Its Voltage Range is .03 - 4.5 VDC. The Voltage is how the Gauge Sweeps as the Sensor Grounds.


1. Manual Transmission Equipped Engine Idle Strategy:

On Manual Transmission Equipped Models the Signal Voltage is part of the PCM Program Cold/Warm Engine Run Strategy and is received on Circuit #37 ensuring IVS Signal Voltage maintains idle..

2. Automatic Transmission Engine Idle Strategy:

On Automatic Transmission Equipped Models ECT is NOT part of the Cold Engine Run Strategy (EOT and IAT determines the IVS Signal Voltage for idling) Circuit #10.

When the EOT reached 130*F - 150*F (Circuit #38) on Automatic Transmission Equipped Models, the ECT becomes part of the Warm Engine PCM Program Strategy.

3. Monitoring the ECT:

Monitoring the ECT via the DLC will show erroneous "signal voltage" until the EOT reached the predetermined voltage programing data points to ensure the vehicle idles while in Gear. Then the ECT can be "seen" signaling the PCM. So, If you're monitoring ECT on an Automatic, it will never be correct until the above conditions are met.

ETC/EOC Differences. The ETC/EOC should be no greater than 15*F from each other. On Automatic Transmission Equipped Models its impossible to determine the differences as the test should be performed KOEO Cold Engine.

 

It's almost never correct even then. I had AE ECT readings that spooked me, so I put an IR thermometer and a laser thermometer on the sensor. Both hand-held thermometers agreed with each other, and they decided the ECT reading on AE was lying its *** off.

 

Thanks for the advice. I know everyone swears by Torque Pro, but it didn't work so well for me. Not sure why, but it would kill the engine every time I tried to read codes... I later found Dash Command, which (so far) has worked pretty well.

 

I don't believe the Torque app works on the 2000 trucks and earlier.

 

I think it will kill the engine with any truck if you have it running and try to pull codes. It does this on mine as well. Try it with key on, engine off..

 

According to the PCM pinout, it does not. A truck with an automatic uses pin #37 for the TFT sensor signal.

 

Stinky is a 2000.

Pulling codes - yup, that's an engine-off thing.

 

I'm humbly corrected. I thought I read something about Torque not working on earlier models.

 

I use Torque Pro all the time on my E99. Well, when it happens to have an engine in it, that is

 

Not to highjack my own thread here, but aside from the engine running/not running when pulling or reseting codes, what are the advantages of Torque Pro over Dash Command?