Ok... starting to think this truck I got is a damn mess. All these problems happening with it and have only had it a week.

99 5.4 V8

While driving down the highway the oil pressure was going from the middle and very slightly dropping down just a little bit then bouncing back up. It never drops near low or anything but it is dropping just a little bit then coming back up.

I know its not a true gauge, so what would make it do this. I read lots how others had theirs drop to the low and throw the light then bounce back up, but mine is no where near as severe. My buddy has a 98 and his does not move a spec.

Oil level is good. No knocking or abnormal noises... Faulty sending unit? Or an actual problem?

 

If you DON'T use Fram filters (and I hope you don't), the 1st thing I'd do is put a new sender on it. They're cheap and it will answer the question for you in a heartbeat. If it still acts the same way, you had better pull the pan and make sure you don't have sludge or parts from a Fram filter wanting to block the pick-up screen. If it makes NO ADDED noise when dropping, my bet is the sender.

 

More likely a faulty gauge in the cluster.

The sender switch's output is binary, either on or off. It should not be able to produce an indication on the mechanical gauge that varies.

The filter, whether Fram or not (sheesh!) has nothing to do with it.

 

When I run the diagnostic by holding the trip/odo and turning the key, the gauge test has them all going up and down smoothly. When I get to the oil part, it shows 255 when the truck is not running and 000 when it is running. Most people say it says 000 when running or not. So it may indeed be the sender?

 

You do know the gauge is a "fake" and sits at 2/3's anytime there is enough pressure to trip the switch in the sending unit.

 

Ya I said that above.
So it seems most likely a faulty sending unit. They are cheap so I will start there.

 

It DOES IF the fluctuation is from intermittent clogging of the pick-up screen, and you bet your life it has happened with Fram filters coming apart. (note, that IS NOT what I said I thought the most likely cause was).

 

I do agree. It is still there for a purpose. So if you ARE losing pressure, getting it back, loosing it, you will see it dump and jump. I could time my watch by mine. It never went anywhere near 0, and it would just slow then bounce back to middle. So if it was a pressure issue, I would think it would dump to 0 and back. Since that is what the switch does, either open or close. I will replace the switch this weekend most likely just to see if that fixes it. If not, its going to the mechanic to find the problem.

 

Well I got the new sending pressure switch but do not know where the heck it is on the motor...? I have an oil filter relocation on the truck so I do not know where it was. Anyone have a picture pointing to where this is? How hard is it to change?

It came with some white stuff on the threads of it, do I still need to use some teflon tape?

Thanks.

The gauge only acts up if I am driving the truck for more than 20-30 mins. It only moves like 1/8" up and down, never drops to the bottom or throws the light. Thats not how it was designed so I really hope it is just the switch.

 

Follow the relocation hoses back to the engine - it will be real near there.

 

Do I have to drain the oil to change the switch??? Dont want to get a face full of oil stream unexpectedly haha.

Also can someone test the diagnostic menu and see what reading they get?
When I run the diagnostic by holding the trip/odo and turning the key, the gauge test has them all going up and down smoothly. When I get to the oil part, it shows 255 when the truck is not running and 000 when it is running. What numbers do you show ON Vs. OFF?

I have not had a chance to change the switch yet. But I did find it. Not sure how the heck I can get in there to change it. Totally cramped. Will try and take the tire off and wheel well liner, see if that helps.

 

Just unscrew the old one and screw in the new one. You do not have to drain the oil.

 

OIL : Displays the code (0-255) for the oil pressure switch input to the HEC. Displays the oil pressure reading input to the HEC. Oil pressure gauge will indicate present oil pressure. Normal oil pressure (greater than 6 psi) will display a value between 000 and 176. A low oil pressure (less than 6 psi) or an inoperative engine oil pressure switch will display a value greater than 176.


the first set of codes is with key on engine off...

gage- all operational
bulb- all operational
r 53
ee 01
dt 7025
dtcd 262
eng 000.0
m 000.0
tach 0000
fuel 064
oil 255
degc 077
br 129
batt 154
rheo
rh. 000?
rhs ff
rho 3e0
cr -he
altf --


now with the truck running and at about 160-180 degrees they are as follows...

gage- operational
bulb-operational
r 53
ee 01
dt 7025
dtcd 262
eng 000.0
m 000.0
tach- idling at about 900 rpm's
fuel 064
oil 000
degc 079
br 129
batt 180
rheo 000
rh. 000?
rhs ff
rho 3eo
cr -h
altf --

 

More info on it.


To enter the HEC ( Hybrid Electronic Cluster) Dealer Test Mode, depress and hold the instrument cluster SELECT/RESET button and then turn the ignition switch to the RUN position. Continue pressing the SELECT/RESET button (five seconds) until tESt is displayed in the odometer. The SELECT/RESET button must be released within three seconds of the odometer displaying tESt 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 continuous DTCs stored before proceeding to the next step.



Odometer Display Description

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; REFER to Instrument Cluster .

All segments illuminated : Illuminates all odometer segments. If any odometer segment is inoperative, INSTALL a new instrument cluster; REFER to Instrument Cluster .

bulb : Illuminates all micro-controlled lamps and LEDs (low oil pressure/high coolant temperature, low fuel, service engine soon, brake, low range). INSTALL a new bulb or LED as necessary.

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

EE : Displays hexadecimal value for EE level (used when requesting assistance from the hotline). If alternating flashes of FAIL and EE level are displayed, INSTALL a new instrument cluster; refer to Instrument Cluster .

dt : Displays hexadecimal coding of final manufacturing test date (used when requesting assistance from the hotline).
dtc : Displays continuous DTCs. 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 is not received, if input received is invalid for one second or more, or if speed is 0.

m : Displays the English speed data (mph) received from the PCM via the SCP network. Displays the metric speed in kph. Speedometer will indicate present speed within tolerances. Display will show 0 if input is not received, if input received 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. Tachometer will indicate present speed within tolerances. Display will show 0 if input is not received, if input received is invalid for one second or more, or if engine rpm is 0.

FUEL : Displays the actual A/D fuel level. The fuel gauge will display a filtered fuel level value. This filter will keep the pointer from moving suddenly or erratically. If the value displayed is between 0 and 20, the circuit is shorted. GO to Pinpoint Test D .
255=open send +/-0
232=Full stop +/-10
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 (0-255) for the oil pressure switch input to the HEC. Displays the oil pressure reading input to the HEC. Oil pressure gauge will indicate present oil pressure. Normal oil pressure (greater than 6 psi) will display a value between 000 and 176. A low oil pressure (less than 6 psi) or an inoperative engine oil pressure switch will display a value greater than 176.

dEGC : Display of engine temperature in Degrees C input from cylinder head temperature sensor. If the value displayed is -40C, the SCP message for engine temperature has not been received for more than 5 seconds. GO to Pinpoint Test E .
49 C="C" mark.
60 C=Normal band start.
120 C=Normal band end.
119 C=Temperature warning indicator ON.
"-40" C=No SCP Message for 5 sec.

br : Displays the brake fluid level input to the HEC.

bAtt : Displays the code (0-255) battery voltage input to the HEC. Battery voltage gauge will indicate present battery voltage.
93-102=6.9-9.1 volts (Low voltage)
115-124=8.5-10.7 volts (Norm band start)
215-225=15.8-18 volts (Norm band end)
230-241=16.9-19.1 volts (High voltage)

rhEo : Displays the present hexadecimal value for the instrument cluster backlighting pulse width modulated (PWM) input to the HEC (used when requesting assistance from the hotline).

rhi
rhS
rho : PWM input duty cycle.

SCP hexadecimal dimming step (used when requesting assistance from the hotline).
Output driver counts in hexadecimal format (used when requesting assistance from the hotline).

Cr : Displays the present RUN/START sense input. Display will show -L with the ignition switch in the START position and -h with the ignition switch in the RUN position.

ALtF a : Displays 8-bit hexadecimal value for alternate fuel level. Display will show a value between OO and FF if the message is received.

PA-PE7 : Not used.

GAGE : Repeats test display cycle.

a : Refer to 413-01B (F250 only).

Turn the ignition switch to the OFF position or press and hold the SELECT/RESET button for three or more seconds and release to exit HEC Dealer Test Mode. If no DTCs related to the concern are retrieved, proceed to the Symptom Chart to continue diagnostics.

 

Thanks!!!