VSS Problem ( not the usual one)

[Sydney]

Hi,
I have an EJ20 fitted to a 1975 bay and have a Brantz BR4 VSS installed between the speedo cable and the speedo. The problem is that it causes the speedo to jump around, quite violently at low speeds, and clicks very loudly while driving. I undid it tonight and it feels like there is a bit of resistance at each of the 4 'pulses' as it rotates.

Has anyone else had this problem with this type of VSS?

It has three wires, +ve, ground and ECU. Does anyone know if the RJES VSS has the same wiring and if it might be a direct replacement?

Thanks.

[Sydney]

Does anyone know what the ECU uses the VSS data for?
Is it simply to tell the ECU that the vehicle is moving in which case the VSS pulse rate is not relevant as long as it is pulsing?
Or does the ECU need to know how fast the vehicle is moving in order to adjust the fuel, emissions, or something else, in which case it's important to feed it with the correct pulse rate for the speed.

The reason I ask is that some sensors output 4 pulses per revolution and another outputs 5 per revolution, and I want to understand if it makes any difference to the ECU.
Thanks

[Kai]

[Sydney]

Thanks Kai. I may get an Rjes sensor then. sounds like it might be a direct replacement.
I can't understand why it's doing it. I'd like to take it apart but worry that it would never work again. I might disconnect the vss from the speedo for now to avoid damaging the speedo.

[Kai]

I'd strip it. It doesn't work anyway so you have nothing to lose by taking it apart.
_________________
Think......

Don't sleep and drive!!!

[flowervanman]

I had the same problem after fitting an rjes vss, I cured it by repacking the back of the speedo with grease. Might not be your problem but worth a try!

[Sydney]

I've done some further investigation. It seems that it's not the sensor afterall but possibly the cable. The clicking occurs once per wheel revolution not 4 as I first suspected. I tried connecting the cable directly to the speedo and it continued to jump, however the cable on its own seems to rotate Ok when not connected at all. The cable sleeve was shortened in order to fit the sensor and I think the cable may have been damaged somehow.

How did you gain access to the back of the speedo to repack it Flowervanman? You're right, it's worth giving it a try while I have the dash out.

[flowervanman]

Nice and easy, unscrew the cable from back of speedo, put some grease on ya finger and push it in the hole, I got this tip off another forum and its certainly cured the same problem for me!