Won't start / Intermittent running / P1235 - 2005 Sport Trac

*** EDIT 5/8 - Please note that this issue started out as a misdiagnosis of Transmission issues - and now I"m thinking it is Fuel Pump issues.****
***EDIT 5/10 - Removed from 911 thread, no longer 911

Well, after my excursion in the mountains this weekend, I get in my truck to drive to work (about an hour after getting home from mountainous drive where I used cruise control.. Hope this wasn't the main cause of the problem) get halfway down the road, and I noticed that the truck stuttered while at about 20 mph maybe 1st or between 1st / 2nd gear- Then the orange Transmission light came on.

I cautiously popped it into reverse, and rolled right back up into my driveway (same noticeable jittery/stuttering- almost like the truck was starving for gas -


Earlier this weekend, and a few times before, I've had it stall when putting it into Drive over and over - only to fix itself after a 2-3 minute engine-off, and restart. The last time this happened was Sunday driving up a ramp in a parking garage - it just stalled.. 5 minutes later, no issues it seemed and it started right up. I don't think it's related, but heck if I know!

I'm at work now - didn't really have any time at all to attempt diagnosis, and I know this isn't enough information, just thought I'd get a posting up here asap. I'll likely begin with a simple fluid check/top off- maybe bust out with an all out pulling of the pan, fluid/gasket/filter replacement..

Any thoughts?

Ran home on my (short) lunch break and checked the fluid on it (cold though) and it seemed fine- A little black on the rag, but that may have been from the top of the dipstick.


What would be my best course of action - obviously not drive it anywhere- Would I be able to pull a code for the transmission with a code reader if the check engine light isn't on but the transmission light is?

From what I've read so far on the issue, I'm suspecting (and hoping) that the issue is only the EPC Solenoid.

Does this sound like a logical suspicion, based on my symptoms? Again, I know I don't have much in terms of symptoms, but what kind of things can I do or try to further narrow down the issue?



I also found a used transmission from a wrecked 2002 Sport Trac w/ 36k miles for a fair ~$800 - would that be the same transmission as my 2005? That is a decent price, no?

Yes Check engine light is for the engine, OD light flashing is for the trans. Pull the trans code and go from there.

PopRichie77 said:

Yes Check engine light is for the engine, OD light flashing is for the trans. Pull the trans code and go from there.

Click to expand...

I haven't really noticed od light flashing but ill check again

Also, if the check engine light isn't on, but the transmission light is, it will still pull a code, right? I don't want to drive it anywhere, or trailer it quite yet - I think I'll run up to Advance and grab a obdII scanner.

Not all OBDII scanners can read manufacture specific trans codes. Sorry, got mixed up, some how I thought you said the OD light was flashing. If the OD light didn't flash then there won't be a code.
After rereading your post it could be an engine problem, even though the check engine light didn't come on. As long as the trans doesn't slip, driving it should not hurt the trans.

Picked up a obdII tool prior to seeing your post, here's the code it provided:

P1235 MOD$10 - which would explain my initial diagnosis

(same noticeable jittery/stuttering- almost like the truck was starving for gas -

Click to expand...

Freeze frame information (Unsure if it's necessary since we now know there's something up w/ the fuel pump)

Abslt TPS 20%
Eng Speed 956 RPM
Calc Load 43.9%
MAF 6.47 (gr/sec)
coolant 172* F
IAT 66F
IGN Advance 17.0 Deg
ST FTRM1 12.5%
LT Ftrm1 .7%
ST Ftrm2 4.6%
LT Ftrm2 -1.6%
Veh Speed 13 MPH
Rel FRP 134.22 KPA
Fuel Sys 1 clsd
o2sII .025v
st ftrmII 12.5%
o2s12 0v
stftrm12 99.2%
02s21 .045v
st ftrm 21 4.6%


At this point, I'm not saying there is absolutely nothing wrong with the transmission, but I'm thinking I may have misdiagnosed the issue in the first place.


Does the fuel pump seem like it would be causing this?


PS.. Also, all the times I mentioned a 'transmission' light... I think I was just an idiot..

I think it's IS the check engine light...

Side note your and my 05 have the 5r55s prior to 04they were 5r55w i would never replace a s with a w(not as good)
On th your code-
P1235 - Fuel Pump Control Out Of Range

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Possible causes

FP circuit open or shorted. ETC system concern (check for ETC DTCs). Damaged FPDM. Damaged PCM.

Symptoms

- Engine Light ON (or Service Engine Soon Warning Light)

P1235 Description

The DTC indicates the FPDM detected an invalid or missing FP circuit signal from the PCM. The FPDM sends a message to the PCM through the FPM circuit, indicating this failure was detected. The PCM sets the DTC when the message is received. Note: For LS6/LS8 and Thunderbird, the FPDM functions are incorporated in the Rear Electronics Module (REM). Also, the REM does not use an FPM circuit. Diagnostic information is sent on the communication link.

Possible solution

The FPDM sends a 25% duty cycle (250 ms ON, 750 ms OFF) through the FPM circuit to the PCM while the fault is being detected by the FPDM. If the fault is no longer detected, the PDM returns to sending an all OK (50% duty cycle) message to the PCM. For ETC applications, check if ETC DTC P2105 is present. An ETC system concern could cause P1235, and should be diagnosed first.

P1235 Information for specific makes

P1235 FORD


Sounds like a bad fuel pump..had one go in my 04 taurus and it worked 50/50 ended up discovering the recirculate valve was sticking causing intermittent lack of fuel pressure thus same symptoms you've had...
Plus my x had a fuel pump put in under warranty for sending unit issues known to these explorers...

This is a fuel injected engine if the pump stops so will the engine. Not uncommon for a pump to be intermittent but also could be wiring or the fuel pump relay, I would bet on the pump but it's just a guess on my part.

Well I feel lucky...

As a first costless troubleshooting step, and by suggestion on someone else having that same code, I swapped my fog relay with the fuel pump relay to test it, and cleared the code. Drove it around, and to a diner, where I sit now. No check engine light, luckily, so far- and it drives and feels normal.. Fog lights work too...

Easy fix? Yes. Is that the only issue? I hope!

Thank you richie, and will for your suggestions- Hopefully I will not need to troubleshoot further!

Thanks for the reply, hope your problem is solved.

PopRichie77 said:

Thanks for the reply, hope your problem is solved.

Click to expand...

Well it drove flawlessly for about 20 miles total with no Check Engine light- then I went out to check on it during my first break here at work- Check engine light is back on, and it stutters when starting.

Weird.. I'm thinking I'll look into fuel pump replacement I guess...

theluke19 said:

Well it drove flawlessly for about 20 miles total with no Check Engine light- then I went out to check on it during my first break here at work- Check engine light is back on, and it stutters when starting.

Weird.. I'm thinking I'll look into fuel pump replacement I guess...

Click to expand...

Can I go ahead and rule out the Fuel Pump Inertia Switch, since it starts and runs? Or would the FPIS also cause stuttering like what I"m getting (and cause a Check Engine light)?

**EDIT made sure the connector was on good for the FPIS, and pushed it a couple times to make sure.. Nothing really clicks, its just a soft rubber button up top..

Ok - so I went and purchased another OBD scanner right next to my work here (since my truck is at work with me in non-running condition) to try what 'fixed' it earlier so I can drive it home.

Cleared the code, started, and it died- turning on the CEL again

Now, I can't get the obd scanner to read a code at all on it, so I'm thinking the fuse for it is popped or something, I"ll check when I get off.

Also, the truck won't start at all at this point. I'm on the third floor of a parking garage, so I'm not sure what I"m going to do - (my dumbass...). There is a sears automotive if worse comes to worse right outside the parking garage.

Here's a video of what happens when I try to start it. Also, I don't hear the fuelpump when I turn the key, but I do hear one small click (relay?)

Found this.. dropping it here for later refererence:

KB30 DTC P1235 OR P1236: IS DTC P1235 OR P1236 PRESENT IN KEY ON ENGINE OFF OR ENGINE RUNNING SELF TEST?
Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Note: For LS6/LS8 and Thunderbird, the FPDM functions are incorporated in the Rear Electronics Module (REM). In the following steps, if directed to perform an action with the FPDM, complete the action with the REM. Refer to the pin numbers in the beginning of this pinpoint test.

Is DTC P1235 or P1236 present in Key On Engine Off or Engine Running Self-Test?
Yes No
A hard fault is present. GO to KB31 to check the FP circuit. DTC P1235 or P1236 is intermittent.

For LS6/LS8 and Thunderbird :

GO to KB42 .

All others :

GO to KB45 .

KB31 CHECK FOR OPEN FP CIRCUIT BETWEEN PCM AND FPDM
Disconnect FPDM.
Disconnect PCM.
Measure resistance of FP circuit between PCM harness connector pin and the FPDM harness connector.
Is resistance less than 5.0 ohms?
Yes No
GO to KB32 . REPAIR open circuit.

KB32 CHECK FP CIRCUIT FOR SHORT TO POWER IN HARNESS
Key on, engine off.
Measure voltage between FP circuit at PCM harness connector pin and ground.
Is voltage less than 1.0 volt?
Yes No
KEY OFF. GO to KB33 . REPAIR short circuit.

KB33 CHECK FP CIRCUIT FOR SHORT TO GROUND IN HARNESS
Disconnect scan tool from DLC.
Measure resistance between FP circuit at PCM harness connector pin and ground.
Is resistance greater than 10,000 ohms?
Yes No
For LS6/LS8 and Thunderbird :

GO to KB36 .

All others :

GO to KB34 . REPAIR short circuit.

KB34 CHECK FP CIRCUIT IN FPDM
Reconnect FPDM.
Key on, engine off.
Measure voltage between FP circuit at PCM harness connector pin and ground.
Is voltage between 4.5 and 5.5 volts?
Yes No
REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM)). REPLACE FPDM.

KB36 CHECK FPF PID
Key on, engine off.
Access the FP and FPF PIDs on the scan tool (the FP PID may be used in the next step).
While viewing the FPF PID for 20 seconds, check if the FPF PID will indicate YES. The FPF PID may read NO in the 20 seconds, but will change back to YES.
Does the FPF PID indicate YES within 20 seconds?
Yes No
GO to KB40 . GO to KB37 .

KB37 CHECK FP PID
Does the FP PID indicate between 70 and 80%?
Yes No
GO to KB38 . TURN KEY OFF then back ON. Wait 5 seconds. REPEAT test step. If result is now YES, follow YES result. If result is still NO, REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM)).

KB38 ACCESS REM PIDS AND CHECK PWM_DC1 PID
Access the PWM_DC1 PID from the REM menu (the PWM_DC1 PID indicates the signal sent to the REM from the PCM on the FP circuit).
Does the PWM_DC1 PID indicate between 70 and 80%?
Yes No
KEY OFF. No fault indicated. Disregard DTC P1235 or P1236. RETURN to Section 3 where DTC was received and proceed as directed. REPLACE REM.

KB40 CHECK REM CIRCUITRY VOLTAGE ON FP CIRCUIT AT PCM
Key off.
Disconnect PCM connector A.
Key on, engine off.
Measure voltage between Pin A58 at the PCM harness connector A and ground.
Is voltage greater than 8 volts?
Yes No
REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM)). REPLACE REM.

KB42 CHECK FP CIRCUIT FOR INTERMITTENT CONCERNS
Key on, engine off.
Access the REM PID access menu on the scan tool.
Access the PWM_DC1 PID from the REM menu (the PWM_DC1 PID indicates the signal sent to the REM from the PCM on the FP circuit).
Observe the PWM_DC1 PID for indication of a fault while completing the following (the PID value will change when a fault is detected):
Shake, wiggle and bend the FP circuit between the PCM (Pin A58) and REM (Pin J2-19).
Is a fault indicated?
Yes No
ISOLATE fault and REPAIR as necessary. KEY OFF. Unable to duplicate or identify fault at this time. GO to Z1 with the following data: PWM_DC1 PID (REM menu), FP PID (PCM menu, the FP PID is the signal the PCM is sending to the REM).

KB45 CHECK FP CIRCUIT FOR INTERMITTENT OPENS OR SHORTS
Key on, engine off.
Access FPM PID.
Note: With no fault detected, the FPDM will send a 50% duty cycle signal (all OK) to the PCM on the FPM circuit. Depending on scan tools, the FPM PID may display 50%, or a random value that is fluctuating between 85 and 115%.

Observe the FPM PID for an indication of a fault while completing the following (look for the FPM PID to change from the 50% value, or to stop fluctuating):
Shake, wiggle, bend the FP circuit between FPDM and the PCM.
Lightly tap on the FPDM (to simulate road shock).
Is a fault indicated?
Yes No
ISOLATE fault and REPAIR as necessary. KEY OFF. Unable to duplicate or identify fault at this time.GO to Z1 .

Tomorrow, plan is to replace the relays for the Computer / Power-train control module / fuel pump and hope for good news.

Beyond that, I am going to look into the Fuel Pump Driver Module - Where will this be located in my Sport Trac?

If no luck on either of these, I'm taking it into the shop. I might even just leave it outside sears tonight, and let them diagnose it in the morning (although who KNOWS what they're gonna tell me.. seems to be hit or miss with sears)

Don't forget the fuel filter, replace one thing at a time and test, I would do the fuel filter and fuel pump first. The PCM drives the fuel pump relay.