[julian bowyer]

Hi
When I start the car the rev counter needle and speedo needle bounce or osolate but no all the time. I start the car and the red battery light off when I move the red battery appears. The battery is reading 12,5v when it is charging the reading is 14.9v when revving 2000rpm when idling 14.6v when the red battery light comes on the charging voltage drops to 13.5v and stays there even when revving to 2000 rpm. I have noticed the trip computer did not work so I detached the battery lead for 5 mins and replaced the lead this did bring back the trip computer. When I start the car and turn the lights on from the start the red battery light never comes on. I can start the engine sit there for 20 mins and the battery light will not come on until I drive down the road. The red light only seems to come on when driving down the road.

[wagolynn]

Search on this forum you will find lots of stuff about the Focus instrument cluster, your symptoms suggest that is the problem.

It's also worth looking on UTube, there may be a video about the problem.

I would also check the alternator drive belt for, condition, and tension.

[julian bowyer]

ford focus 1.8 diesel 2004 battery light on dash

Thanks I have looked through the lights on the dash but nothing relating to my problem. I have checked the belt and the tension both seem ok but it is difficult to tell if the tensioner is fully extended. Thought someone might have some other ideas as to testing before draining my pocket of money.

[wagolynn]

There are three small wires from the alternator, these link to the engine computer, the computer controls the charging.

These wires are prone to failing, Ford does a replacement set, these may be the problem.

[Motman]

I had this problem once on a focus and it turned out to be a 1 or 2 amp fuse in the fuse box that controlled the charging.