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Member Since 04 Oct 2013
Offline Last Active May 06 2014 09:40 AM

Topics I've Started

Focus: Instrument Cluster Erratic Behaviour

08 October 2013 - 10:03 AM

[I originally posted this as a reply to an older thread but feel it may be of use as identifying the problem and also one possible solution. Hope it helps]


Ford Focus Mk1: Instrument cluster erratic behaviour, with (or without) internal/external lights issues (Apologies for verbosity)


This first occured approx 4 years ago. Whilst driving on the motorway (typically I had to be above about 50mph) the speedo sometimes drops to zero, then returns to the correct speed a second or so later. This may then be followed by the rev counter dropping to zero and a second or so later recovering, then the engine management light coming on and going off, the odometer display going to horizontal lines and so on. Sometimes this would be completely at random just happening every now and then. At other times it would happen for several minutes with the dials and warning light going on and off though usually not all together. I found a few forum threads and implemented the removal and WD40'ing of the instrument cluster but this had no effect. (A friend had had a similar problem on his Focus and had found that this cluster connector fix had worked for him **). As the car drove perfectly well with no mis-fires or other safety issues I continued to drive it while monitoring whether the problem was getting any worse.


However, after a month or so it then progressed to another level. As well as the instrument cluster issue it would then have periods with all the vehicle lights flickering including the headlights, internal lights and all of the console illumination. Having found another forum thread, and taking a bit of a punt, I had the battery changed but also had all the earth bonding points cleaned and tightened. All of the issues went away (but it was unclear whether it was a battery fault or the earth bonding). However the important point was that it was nothing to do with the instrument cluster itself but was the primary electrical supply to the vehicle.


4 weeks ago the faults re-occured. This time all of the symptoms started at the same time. Instrument dials dropping to zero, warning lights coming on and off, internal/external lights flickering etc. In a series of tests it seemed that the issue became worse if the A/C was switched on and/or the headlights, heated windscreen, heated rear window or other heavy electrical loading. Again this pointed to an electrical supply/voltage problem. After inspection, I determined that the negative battery terminal was slightly loose - not really loose, you had to put some pressure on it, but it could just about be turned by hand. Also there was some corrosion on the earth bonding point from the neg terminal to the vehicle chassis - this point is located under the air filter box. I cleaned the bonding point and had a new terminal clamp fitted for the battery. Again, since these actions the issues have all gone away.


Both the negative terminal being loose and the bonding point being corroded could cause the voltage being seen by the vehicle systems to be low or fluctuate depending on the load. This in turn could cause the instrument cluster microprocessor to glitch or reset and other systems to misbehave. We can't say whether all such faults can be fixed by such simple remedies but it's certainly worth checking as a first stage before looking at more complex diagnostics. Good luck!



[** End note: the instrument cluster removal / WD40'ing fix that has sorted some owners erratic instruments issue probably has a similar "root problem". Over a period of time the connector contact interface to the cluster may degrade, becoming more resistive and dropping the power supply volts to the instrument cluster by some small amount or affecting sensor signal paths. By disconnecting, lubing and re-connecting the harness, the contacts are cleaned and normal service may resume. Note that if the problem is with the harness connector you would be unlikely to also get the progression to the lighting flickering etc that I had]


Focus: Heater Fan Blower Works Only On Setting 4 And No Aircon

08 October 2013 - 09:09 AM

[I originally posted this as a reply to an older thread but feel it may be of use as identifying the problem and also one possible solution. Hope it helps]


Ford Focus Mk1: Heater fan blower works only on setting 4 and no aircon


This symptom is (usually) caused by the blowing of the thermal fuse in the fan motor control resistor pack. (The resistive power drop is a really cheap way for Ford to control the current, and hence the speed of the fan).The reason the fan works on setting 4 and not on the other 3 settings is that the full speed setting 4  bypasses the resistors and the thermal fuse.[Those with A/C would also find that the A/C doesn't work at all, as it intentionally only works with fan speed settings 1-3.]


This resistor pack is quite awkward to get at as it is located behind the glove box and some ducting for the heated air. The reason it is there is that Ford use the airflow from the fan to cool the resistor pack (which can get pretty damned hot!). However, with some squirming around on your back, a long shaft Philips screwdriver and so on it can be removed and replaced by a "normal person". [The Focus Haynes manual has a small section detailing the heater blower removal and the location of the resistor pack]


In my case I had the A/C and the fan stop working on settings 1-3 a few years ago. The local garage replaced the resistor pack and everything was good again. A month or so later the new pack failed. Initially it was suspected that it was just a faulty pack so they fitted another free of charge. Again a few weeks later this second replacement failed. (This next bit may seem a bit dodgy!) The mechanic said that he had had this happen before on another customers car and that, in some frustration, they had soldered a wire across the thermal fuse to prevent it happening again and this had fixed their problem. With some concerns I gave him the go-ahead to do this and all seemed well until the winter, when the fan blower failed again. As the thermal fuse had been bypassed it didn't seem that this could still be the same issue but ... yes it was. The resistor pack had got so hot that the solder melted and the bypass wire fell off!!


Clearly we had some other issue  - and this is where the cheapness of Ford's design solution comes into play. In my case what was actually happening was that the fan was running slightly slower than expected particularly on setting 1. Some condensation from the A/C, or just incoming moisture, had slightly corroded the bearing for the fan motor so it wasn't turning as smoothly as it should. (In some cases I have heard of them squealing). As the airflow from the fan is used to cool the resistor pack eventually the pack gets too hot and blows the thermal fuse. This is most likely to happen on setting 1 since this has the least airflow and the highest power drop through the resistor pack. 


I removed the blower unit and cleaned and oiled the bearing, replaced the resistor pack (again) and it's still going well 6 years later.