Electrical fault?

[Peter Cluer]

2005 Ford c max 1.6. Brake fluid dash light on, fluid level fine. Interior light stays on. Headlight main beam light doesn't come on, indicators don't tick tock but work, car won't lock. Any suggestions please? Thank you 

[TomsFocus]

Sounds like the common cluster fault, the solder joints dry out and crack causing poor connections.  The clusters can be sent away for repair unless you're good with a soldering iron yourself.  

[isetta]

I agree it could be instrument cluster fault.

But also: one day on my brothers focus mk2.5 the handbrake light stayed on (might be same light as brake fluid level), the blue high beam light did not work, the indicators made no sound (although were flashing outside), the green indicator tell tales on the dash did not work and the outside temperature reading showed dashes instead of the temp. I found something with google which indicated that all those things are controlled by the MS canbus which runs between instrument cluster and the fuse box under the glovebox. There was a suggestion that the connectors get kicked on the underside of the fusebox. Checking that did not fix it but fiddling with another big connector plug which had some iffy looking terminals in it fixed it. I think this connector was on the inner sill near front passenger's left foot . I think from memory it was connector c112. Trouble is, if there are iffy terminals in it, fidddling with it might create other problems as there are loads of wires in that plug).

(don't confuse MS Canbus with HS canbus. They are different and use different wires)

[Tdci-Peter]

On 1/14/2020 at 9:18 PM, Peter Cluer said:

Brake fluid dash light on, fluid level fine. Interior light stays on. Headlight main beam light doesn't come on, indicators don't tick tock but work, car won't lock.

Brake fluid level goes into the GEM, along with Interior light controls, Headlights, Indicators and locking. The GEM or BCM is built into the passenger fuse box, and is quite prone to corrosion due to water or condensation.

It could be an MS-CAN bus fault, like Isetta suggests. This runs from GEM to the Instrument Cluster (IC). If you have front & rear electric windows then it carries the Door locking and Door latched signals, so Locking & Interior light would be affected. It carries all the signals from GEM to IC, so the IC information LEDs would be affected.

It also carries signals from the Restraint Module to the IC, so the seat belt warning chime might be affected, that would be a useful test.

Tom suggests the IC soldering. The MS-CAN bus goes through the suspect connector to the IC, but I am a bit doubtful if this would interfere so badly with door locking & latching (interior light). Technically the termination resistor on the IC can affect the whole bus, but in practice it usually works ok even without it. I suspect door signals should get to the GEM even if the IC connector was bad, so it is worth doing additional tests before removing the IC.

If the main beam headlights themselves don't work, this is not MS-CAN related, they are directly controlled by the GEM. Just the IC status LED goes over the bus.

I suggest additional tests of what does work, as well as what does not. And ideally the use of an in-depth diagnostic system like Forscan, which can test all the stuff on the MS-CAN bus, unlike most generic scanners.