528e speedo sensor - BMW Forum

spivey · 07-02-2008, 11:56 AM

I have an 82 528e that I am trying to install a Cyberdyne digital speedo in. The problem is that I am not getting anything from the stock speedo sender. How much voltage should it be supplying as the wheels spin? The car is on jackstand idling in first gear. I would think that there should be some voltage reading. What should the sender read ohms wise if it is ok? This is a project car for my daughter that has gotten way out of hand.

darkhorse737 · 07-02-2008, 04:48 PM

there is are no given parameters for voltage or resistance for the speedo sending unit.

Since your digital speedo is new, and we assume it to be working, change the sending unit on the rear of the differential. However, if the speedo was working pre-installation of the digital speedo, then assume diff speedo sensor is working, and your problem is somewhere else ;-)

spivey · 07-02-2008, 09:45 PM

Since I made the first post I contacted Cyberdyne's tech support. After being told several months ago that the gauge would work with the stock sender I was told today that it won't work in my application. My question now is can I take the stock speedo out of the original housing and run it without the other gauges. Here's another question can I take the two wires that are coming from the sender and send them directly to the pos. and neg. poles on the speedo? Will this trigger the speedo. I've got about $300 tied up in digital gauges and mounting panel so I'm trying to save as much of the work that I have already done as I can.

darkhorse737 · 07-02-2008, 10:03 PM

My question now is can I take the stock speedo out of the original housing and run it without the other gauges. Here's another question can I take the two wires that are coming from the sender and send them directly to the pos. and neg. poles on the speedo? Will this trigger the speedo.<<<

... i am afraid the answer is NO. The wires you see from the sender are connected to an integrated circuit that provides for the voltage control; and uses the sender wires only to transmit pulses as a means to determine speed.

In my opinion, you should try an contact Cyberdyne and inquire about an altrernative sensor that may be used as a means to determine speed. (ie... ABS wheel sensors.)

* I am not 100% sure, but I believe some 7 series bimmers uses on the rear wheel abs sensor as a speed sensor as well... Even if not, it is worth exploring since the wheels sensors count the rate at which the wheels turn-a calculable basis for speed ;-)

Good Luck.

spivey · 07-02-2008, 10:16 PM

Cyberdyne has sensors that replace a cable drive speedo for Ford and Chevy. I have the Getrag 5 speed. I don't think this trans had a cable drive to it. I was in hopes that I could modify one of these units but I don't think that is going to be an option.

Thanks for the info. I appreciate the help.