2008 Focus LT issues - electrical?

numloxx · 06-11-2019, 03:20 AM

Hi guys,

I'm not quite sure what to put in the title as it's a few things that I'm having trouble with.

I was driving on the freeway in Perth today and suddenly a few warnings came up on my dashboard:
Speed Limited Mode, Engine Systems Fault, Transmission Malfunction, Power Steering Fault. I pulled the following fault codes using the Torque App and an ODB2:
U1900 - Network,
P0571 - Powertrain, Cruise Control/Brake Switch A circuit,
P2121 - Powertrain - Throttle Pedal Position Sensor/Switch D circuit range/performance
U1900 Network

I went back home and disconnected the battery for 30 minutes then connected again. I drove on the freeway again and was going to a friend's house who is more mechanically inclined than I am.

It then came up with:
P0231 Powertrain - Fuel Pump Secondary Circuit Low,
P0571 again
P2121 again
U0073 - Network
U1900 again
U2012 - Network
U2197 - Network
U2200 - Network

I lost my rpm and speedometer and also fuel and battery levels, all went to 0 (fuel and battery a bit slower of course), with all my warning icons. Went away again, with messages as before. I lost power steering this time.

Gauges all fixed themselves and power steering returned. Happened a few more times.
My friend and I did some test driving, and we thought it might either be the throttle sensor, instrument cluster, or the ECU/PCM ?

Any assistance would be greatly appreciated, as I'm hoping to fix this myself, as I'm not in a good spot with work at the moment, casual jobs only, and hoping to be able to fix it myself, but will take it to Ford or RAC if I have to.

On the drive home on the freeway, all was ok.. but driving around my friend's house, the dashboard constantly conked out several times driving under 60km etc.

**russellw** · 06-11-2019, 08:19 AM

I can help decode them and suggest some diagnostics.

P0231 is low voltage on the fuel pump circuit. The PCM monitors the fuel pump monitor. The test fails if the PCM commands the fuel pump ON and B+ voltage is not detected on the FPM circuit.

Possible causes:

Open B+ circuit to the fuel pump relay
Open FP PWR circuit between the fuel pump relay and its connection to the FPM circuit
Damaged fuel pump
Damaged PCM (engine will start)

Pinpoint Tests

Disconnect the inertia fuel shut-off switch.
Disconnect the PCM.
Install a jumper wire between the PCM harness connector pin 80 (FSV) and ground.
Connect a digital multimeter between PCM harness connector pins 40 (FPM) and ground.
Key on. The fuel shut-off valve relay will activate and voltage will be greater than 10.0 volts.
Observe voltage for an indication of a fault while completing the following (the voltage will change suddenly when a fault is detected, indicating an open):
- Shake, wiggle, bend the B+ circuit to the fuel shut-off valve relay;
- Lightly tap the fuel shut-off valve relay to simulate road shock;
- Shake, wiggle, bend the FSV PWR circuit between the fuel shut-off valve relay and the FSVM splice.

• Inspect the fuel shut-off valve relay connector for corrosion and/or damaged pins.

P0571 is a brake switch plausibility error. This DTC sets when the brake switch does not toggle during the key ON engine running (KOER) test.

Possible causes:

BPP circuit open
BPP circuit short to ground
Concern in modules connected to the BPP circuit
Damaged brake switch
Incorrectly adjusted brake switch

I don't have a listing for P2121 in the PCED reference.

Given the rest of the symptoms you are describing I suspect an electrical fault in the wiring somewhere that is of a major nature or a faulty PCM - although the latter would tend to throw a lot of other DTC's as well and the U codes lead me to believe it's probably in the CANBUS wiring.

numloxx · 07-11-2019, 06:30 PM

Thanks for your response. How would I go about testing the wiring to the PCM?
What would Ford charge for something like this? I've got a feeling it's going to be very expensive and time consuming.. would RAC have a good idea or diagnostics and repair for it or Automasters etc or is it best to take it to Ford?

numloxx · 10-11-2019, 02:14 AM

As I was leaving a friend's house this afternoon, the faults came up again, I hit the top of my dashboard and it fixed it. After I got home, I removed the instrument cluster pulled it apart and sprayed it with contact cleaner and installed it again. Drove 50km tonight on the freeway to test it and so far, no faults... fingers crossed

**russellw** · 10-11-2019, 07:27 AM

Hope it does fix it - seems likely that it might have been a bad earth or a bad contact somewhere in the cluster but I guess you'll never know.

numloxx · 21-12-2019, 05:34 PM

Started having issues again the last few days but not as bad. Seems to be the heat. Trying to find a replacement cluster. Any idea how to program them to set the value for the odometer?

marg99 · 21-12-2019, 06:07 PM

confess I thought the Body Computer module retained that information but could be wrong

falcon95 · 22-12-2019, 03:12 PM

Numloxx, Heres 2 vids you may find useful about repairing dry joints in the soldering of usually the BUS connectors in these dashes....
https://www.youtube.com/watch?v=ei7JguJ0apE

https://www.youtube.com/watch?v=Ldm8ByHp5lE

cya
falcon95

numloxx · 22-12-2019, 03:56 PM

Thanks. Yeah I have seen that first video before, this is how I learnt how to open it up etc. I suppose I could just buy a new unit (2nd hand) and plug it in to see what happens. I've heard that codes for the keys might be stored in there too?

mumfy · 26-12-2019, 07:46 PM

sorry to hijack this but my daughter has a Focus LV 2011.....

and its having the same issues

P0460,P2121,P2122,B1318,B1204,B1868, and C1750

I reckon the cluster requires replacement.....

numloxx · 05-01-2020, 02:46 AM

Remove the cluster, open it up, spray it with contact cleaner, if it fixes it for a while then it's stuffed. I had to solder the connectors again because spraying it didn't work.. still ok after 200km, but if it occurs again I'll buy a 2nd hand unit.

numloxx · 07-01-2023, 06:10 PM

2 years later and still no issues. The connector to the instrument cluster needed a good solder reflow and that fixed the issues. I think it came up 1 or 2 more times since, but other than that it's been good. Got a feeling it's heat related.

290v · 18-01-2023, 08:24 PM

my daughters had problems like this was going to change cluster but on inspection of the fuse box under the glove box there is two plugs and my grand-daughter had knocked one loose when she drove everything was good. but all of a sudden everything stopped working again codes would be coming up on the scan tool so before you start look at the two big white plugs on the fuse panel under the dash if you have them

Rs31markie · 25-01-2023, 11:23 PM

Hi, it sounds like it could be similar to a fault I had, various faults come up on dash and a no start. I could hit dash and it would start. I traced the problem to cracked soldered joints on the back of the dash. YouTube it, it’s very common. Hope this helps

numloxx · 31-01-2023, 07:04 PM

Quote:

Originally Posted by Rs31markie

Hi, it sounds like it could be similar to a fault I had, various faults come up on dash and a no start. I could hit dash and it would start. I traced the problem to cracked soldered joints on the back of the dash. YouTube it, it’s very common. Hope this helps

Yes that's exactly what my fault was.
The random fault codes were due to data corruption. Dry solder joints on the cluster pcb connector. I reflowed the solder and all was good.
Has come up again once a few years ago, but nothing since.