On a 770 mile trip...about half way down, my Service Engine Soon light came on. I thought it may have been the gas cap since it was not long after I filled up that it illuminated. Well it wasn't that it seemed. Following a reset by removing the positive side cable from the battery and allowing it to sit for 4 hours (once we were at our destination ) the light went off. On the next and subsequent use of my truck...no issues, no light. After a couple of days I had to travel again....halfway through the trip...BAMo! Light back on. I didn't bother to reset it since I wouldn't be back at my families for a couple of days....I figured I'd reset it then...well once I arrive back at my families..it was still on. Went to go see a friend of mine and it mysteriously went out on its on. No reset. If I remember correctly those lights just don't go out with out a reset.

Any ideas? I'll verify the bulb is not burned out tomorrow.

Truck is a 2000 F150 4x4 5.4L everything stock with 90K miles.

 

Go to autozone and have them check it, come back and search the code...Re-setting the battery 50 times isn't going to fix your truck.

 

As I thought I clearly stated, the battery was only used one time to clear the light (thinking at the time it was a gas cap issue). What I'm looking for is not only information on the Service Engine Soon light...yes I know I need the code and don't worry I'm getting a code reader as soon as I get home, but also, if someone has had this happen where the light went off by itself. I've never had that happen. Once the light came on, it was on until the situation was fixed and the computer reset....this one reset on its own.

My apologies for misleading you into thinking I reset it "50 times". I didn't think I said or implied that.

 

There are numerous codes that can be set by a one time occurrence.

These codes will be stored in memory, so can be pulled once you get home or wherever you are waiting to be.

When the light turns off, it doesn't mean the cause of the the light is fixed, and frequently means there are numerous possible reasons for the light to have been on.

Get the codes read ASAP.

 

With the light off, the code is gone.

After 2 drive cycles ( sustained over 48 MPH ) if the problem is not seen on either drive cycle, the code will be cleared and the light goes off on its own.

You would need to have the light on, to get a code.

If you have not changed your gas cap, it could be that. I know on my first EPA inspection, the light was not on, and my gas cap failed the test. So it could be that, or something else. Next time try using the HEC DTM, to see if the code is registered. This is done with the engine off most of the time, so you will see an oil pressure low DTC.

Activating Test Mode

To enter the HEC Dealer test mode, depress and hold the instrument cluster SELECT/RESET button, turn the ignition switch to the RUN position, and then continue pressing the SELECT/RESET button (5 seconds) until tESt is displayed in the odometer. The SELECT/RESET button must be released within 3 seconds of the odometer tESt display to begin the dealer test mode.

Depress the SELECT/RESET button to advance through the following steps until dtc is displayed. Depressing the SELECT/RESET button will display any stored continuous DTCs before proceeding to the next step.

GAGE
Activates gauge sweep of all gauges, then displays present gauge values. Also carries out the checksum tests on ROM and EE. If the gauge sweep is inoperative, INSTALL a new instrument cluster.

All segments illuminated
lluminates all odometer segments. If any odometer segment is inoperative INSTALL a new instrument cluster.

bulb
lluminates all micro-controlled indicators and LEDs. Install a new indicator or LED as necessary.

r
eturns to normal operation of all micro-controlled indicators and LEDs and displays hexadecimal value for ROM level. (used when requesting assistance from the hotline). If alternating flashes for FAIL and ROM level are displayed, INSTALL a new instrument cluster.

EE
Displays the hexadecimal value for EE level (used when requesting assistance from hotline). If alternating flashes of FAIL and EE level are displayed replace instrument cluster.

dt
Displays hexadecimal coding of final manufacturing test date (used when requesting assistance from hotline).

dtc
Displays continuous DTC's in hexadecimal format. Pressing the SELECT/RESET button will display any DTCs stored before proceeding to the next step.

enG
Displays the English speed in MPH. Speedometer will indicate present speed within tolerances. Display will show 0 if input in not received. If input is invalid for one second or more, or if speed is 0.

m
Displays the metric speed data in kph. Speedometer will indicate present speed within tolerances. Display will show 0 if input in not received. If input is invalid for one second or more, or if speed is 0.

tAc
Displays the tachometer data received from the PCM via the SCP network within tolerances. Tachometer will indicate present RPM. Display will show 0 if input is no received, if input received is invalid for one second or more, or if engine RPM is 0.

FUEL
Displays the code (0-255) for the fuel sender input to the HEC. The fuel gauge will display a filtered fuel level value. This filter will keep the pointer from moving suddenly or erratically.
255 open send +/- 0
232 full stop +/- 0
215 Full mark +/- 10
178 3/4 mark +/- 8
138 1/2 mark +/- 7
93 1/4 mark +/- 5
41 E mark +/- 4
54 Low Fuel (0-59)
0-18 short (0-20 max)

OIL
Displays the code (0-250) for the oil pressure switch input to the HEC. Oil pressure gauge will indicate present oil pressure. Normal oil pressure (greater than 6psi) will display a value between 000 and 176. A low oil pressure or an inoperative engine oil pressure switch (less than 6 psi) will display a value greater than 176.

dEGC
Display of engine temperature in Degrees C input from cylinder head temperature sensor.
49 C "C" mark
60 C Normal band start
120 C Normal band end
-40 C No SCP message for 5 seconds

bAtt
Displays the code (0-255) for the battery voltage input to the HEC. Battery voltage gauge will indicate present battery voltage.
93-102 6.2-9.1 volts, low voltage
115-124 8.5-10.7 volts, Normal band start
215-225 15.8-18 volts, Norm band end
230-241 16.9-19.1 volts, high voltage

rhEo
Displays the present decimal rheostat dimming input, 0-255 (used when requesting assistance from the hotline)

rhi
not used

rhS
not used

rho
not used

Cr
Displays the current RUN/START sense input. Display will show -h for high input with the ignition switch in the START position and -L for low input with the ignition switch in the RUN position.

PA-PE7
not used

GAGE
Repeats the display cycle

Source: Helms 99 manual.

 

Have to differ.

The DTC is stored in the PCM for a minimum of 40 (usually 80) drive cycles. It is NOT erased. The turning off of the light simply indicates that the diagnostic test didn't fail the most recent time(s).

The HEC Dealer Test Mode does NOT read PCM DTCs. It can only post fault codes for the portion of the sub-systems that the cluster processes s indicated by the list you provided. As most causes for the MIL are emissions or performance related, performing the HEC test is unlikely to provide any data of use.

As poster #2 said, go get the code read.

Steve

 

Sorry for taking so long in posting this....I did go get the code read it was something to do with the upstream DPFE Sensor hose off or tube clogged (I can't remember the code)....Any way....once I investigated I notice the hose closest to the firewall was easily removed but the front one didn't come off at all....upon further inspection I noticed the back one was split. VOILA!

Changed the hose out....and the light has never come back on!!!

Apparently during the trip the hose finally broke down...and split....thus the code. It was just time for it to fail.....just peculiar that's all....but long trips..and heat can break down hoses!