I currently have an issue where the fuel level gauge is not indicating a level, and the outside temperature gauge is not reading.. The trip computer is not indicating a range even though the other functions for MPG, Average MPG, Distance travelled etc. This is on a 58 plate Greenline. Has anyone experienced this before, or has any idea if a fuse covers these items - cannot find a wiring diagram anywhere for the Mk 2 to allow a trace of the wiring - as there is nothing in the fusebox layout.

I'd be reasonably confident that there isn't a fuse specific to these functions, but from memory of reverse-engineering part of a mk1 Fabia cluster, the same (PCB chip) voltage source is used on both functions (and little if anything else). I would suggest finding and disconnecting the outside temperature sensor just in case that (or its connections) is shorting out the system, bringing both functions down. Usually just near where a nearside foglight would be if fitted, behind front bumper.

Edited 16 July, 20205 yr by Wino

Some parts of the display went off after a static cloth may have been used to wipe the cluster's screen. Might be worth popping the battery neg lead off for a little while, then putting it back on to see if all comes back or not.

Had it scanned and following issues returned. I have bought a 2nd hand instrument (5J0920911C) console for £12.50 so hoping to review pin-outs. While I know that this will not be useable without coding, are there any issues with just plugging in to identify if it is a PCB issue, or car wiring, as I believe that the fuel sender and temperature gauge will act as variable resistors to give the required readings. I have still to identify/disconnect the outside temperature gauge suggested by Wino. 

 

2 Faults Found:
00771 - Fuel Level Sensor (G) 
            30-00 - Open or Short to Plus
00779 - Outside Air Temp Sensor (G17) 
            30-00 - Open or Short to Plus

Seems like a reasonable strategy to me. I'd think it will work enough to prove the point. 

I can find the pinouts relating to those functions for you, but tomorrow rather than now.

Sorry, forgot to look at this yesterday. what year is the car?   58-plate, so pre-March 2010.

 

Outside temp seems to be a brown/yellow wire on pin 31 of the 32-way cluster connector. Fuel gauge is lilac/black wire on pin 15.  Both earth via a brown/white wire going to pin 32.

 

From march 2010 it looks like outside temp moved to pin 19, and fuel gauge is done differently, using all three connections of the potentiometer (pins 1, 2 and 20 at cluster). Brown/white on pin 20 is the earth for both systems.

 

Checking that earth wire isn't busted, or suffering a cracked solder joint is probably a good starting point.

Edited 21 July, 20205 yr by Wino
Noticed age of car is in OP

3 hours ago, Wino said:

 Outside temp seems to be a brown/yellow wire on pin 31 of the 32-way cluster connector. Fuel gauge is lilac/black wire on pin 15.  Both earth via a brown/white wire going to pin 32.

 Thank you for the info. I assume that metering across the pins in the plug will give a limited resistance on fuel sender and outside temperature sensor and not show lack of continuity (no buzzing on my meter) to prove if this is an issue external to the cluster. Also assume the signal from these pins into the cluster could not be checked as the resistance will be transferred into the display value via a processor.

Since your errors both say open or short to plus, I'd think it's most likely a connector pin whose solder joint has cracked, a dirty/corroded connection or a wire break.

 

Measuring Ohms between loom connector pins 31 and 32 should give you a resistance that will depend on fuel level in tank. (Or open circuit/infinite if there's a wire break, or near zero if the thing at the end is shorting).

Repeat for pin 15 to pin 32, expecting again a resistance that will depend on outside temperature.  

 

If both of those check out OK, I'd be getting to the solder joints of the 32-way connector on the cluster circuit board and giving them an extremely careful eyeballing. 

This is a pic of a mk1 cluster showing the joints in question (ignore the marked pins, may be different on mk2).  I think if the connector is oriented the same on mk2s, pins 31 and 32 are the leftmost of the nearer row; 15 on back row opposite 31.

 

 

Quick update. Following Wino's - thanks for the info, your wiring/electrical issue understanding continually assists many issues - suggestion I got the meter out and found while the fuel gauge was showing resistance there was continuity through pins 15 to 32 with no resistance, I didn't plug the spare instrument console in as I am still unsure of possible issues with the unmatched immobiliser and especially the radio which I don't have the code for. I can actually read the fuel level through Torque and a bluetooth OBD2 adaptor suggesting the sender is good, although it is saying 50% full with a full tank and the remaining range is showing at about the correct distance. but I can't read ambient temperature through it.

 Next job is to locate the outside temperature sensor and unplug this. 

 Fitted the alternate instrument cluster and the fuel level and outside temperature are showing readings, but obviously the immobiliser stops the car starting. I checked the pins as Wino recommended and there is continuity from the pins to the inside soldered connection and the next contact point when following the track on the PCB, so appears that it may be the signal converter on the PCB. I even swapped the trip computer LCD screen and have the same issue. I will carry on using the trip mileage covered, and the Torque app.

Edited 1 August, 20205 yr by KeithCheetham