Speedometer wobble

[Johnie Boy]

Like Leighfos’s post in the Fiesta forum on 25 May 09, the speedo on my wife’s Fusion 1.4 (53 plate) bounces, wobbles, and overreads, then settles down for a while, before starting off bouncing again.

I am fairly sure that the Fusion has an electronic speed sensor fitted to the transmission in place of an old-style speedometer cable (but there is no Haynes manual for the Fusion – they say to use the Fiesta Mk5 one instead).

The bouncing speedo problem may have started when I changed the clutch and had to disconnect all the cables etc from the transmission/gearbox area. I had difficulty disconnecting the speedo cable connector, so I removed the whole sensor (as if an old-style cable). The sensor had been bound in foil tape, which I unwound before removing the sensor. I rebound the sensor with the same tape on re-assembly.

I suspect the bouncing is because either the sensor is dirty or damaged, the cable connections are dirty or broken, or the tape binding is inadequate. I have briefly tried re-attaching the cable connections and re-binding the sensor, but got no improvement.

Before I try replacing the sensor itself, I would be grateful if anyone had any suggestions, or knew how to find what is really wrong?

Thanks

JohnieBoy

[paul-eb]

Like Leighfos’s post in the Fiesta forum on 25 May 09, the speedo on my wife’s Fusion 1.4 (53 plate) bounces, wobbles, and overreads, then settles down for a while, before starting off bouncing again.

I am fairly sure that the Fusion has an electronic speed sensor fitted to the transmission in place of an old-style speedometer cable (but there is no Haynes manual for the Fusion – they say to use the Fiesta Mk5 one instead).

The bouncing speedo problem may have started when I changed the clutch and had to disconnect all the cables etc from the transmission/gearbox area. I had difficulty disconnecting the speedo cable connector, so I removed the whole sensor (as if an old-style cable). The sensor had been bound in foil tape, which I unwound before removing the sensor. I rebound the sensor with the same tape on re-assembly.

I suspect the bouncing is because either the sensor is dirty or damaged, the cable connections are dirty or broken, or the tape binding is inadequate. I have briefly tried re-attaching the cable connections and re-binding the sensor, but got no improvement.

Before I try replacing the sensor itself, I would be grateful if anyone had any suggestions, or knew how to find what is really wrong?

Thanks

JohnieBoy

Have another look at the cable, you may have kinked it causing it to flick as it turns.

I know you are probably sick working on it, but i'm guessing this might be the problem.

Best of Luck Paul-eb

[Johnie Boy]

Thanks Paul-eb

But it is not a "cable" that turns in a sleeve - it is an electrical wire ending in a plug connector (that I couldn't see how to separate so I had to take the whole sensor out). The wire may be broken and making only intermittent connection (but I don't think so). I wonder more if the foil tape is not shielding the sensor properly (or something like that)!

Cheers

JohnieBoy

-------------------------------------------------

Have another look at the cable, you may have kinked it causing it to flick as it turns.

Best of Luck Paul-eb

[Jimgeriatric]

Hi all

I am having this exact problem driving along at 50mph and suddenly needle goes to 70 then Back to 50 then to 100 down to 70 and then back to 50 waves between 50 and 70 then settles at 50. Have googled problem found nothing as of yet.

Regards to all jim