Cosmo Kramer

Hi all

Chasing an ABS light on my S4 (on immediately when I start the car), tested CE relay it's good, checked fuse, checked wire terminal block by PS pump all good. Moved to the two relays on the pump itself. The silver relay with 6 prongs, it flows power closed and open. According to the diagram on the relay there is a diode on terminal L1, when I test through that circuit with my ohm meter I am getting a reading of 127 on my 200k ohm scale. From my understanding the diode is just supposed to flow power one way and not have any resistance. Can someone verify this? If this is the case I believe the diode inside the relay is done.

the flyin' scotsman

a good diode should measure infinite in one direction and essentially zero ohms in the other unless its a zener

Cosmo Kramer

It measures infinite in the one direction and 127k in the other, so I suspect it is done and keeping the pump from starting up.

oups59

I am still chasing the same issue.....

SMTCapeCod

ANy updates here?

dr bob

The diode testing should measure voltage drop in both directions. Reverse is infinite ohms and voltage drop. Forward voltage drop varies based on type of diode and substrate. Ohms are really not predictable, since they depend on the type of meter used. For silicon diodes, look for about 0.67 volts forward voltage drop.

Cosmo Kramer

I grabbed another relay from the local Porsche wrecker here, it too measures resistance so confirms what Bob said above. It measures less resistance then mine, I just haven't had a chance to get it installed yet. I will report back when I do.

Cosmo Kramer

Well, unfortunately the spare relay hasn't fixed the problem. Next I guess is to verify I have power to the pump, possibly the pump is defective. .

Cosmo Kramer

Ok have some time and diving into this some more. I have replaced both relays on the pump still have the immediate abs light on startup. I jumped 30-87 on the CE panel and I can hear the relay in the wheel well clicking, but I still have the abs light when I start it up. I also confirmed that I have 12v to the abs terminal block. What's the next best course of action?

oups59

Cosmo,

Take a look at post #27

I had the same issue....

Cosmo Kramer

I will check that out for sure, if that connector was bad would I still hear the relay in the front fender clicking? It sounds like my relays on the pump are powering up when I jump the CE panel ABS relay but the light remains on at startup.