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Re: ABS relays - how to test them...?? Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Wed, 5 May 2004 06:58:32
In Reply to: ABS relays - how to test them...??, Zip, Wed, 5 May 2004 06:15:10 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Relays pretty much work or they don't. For the kind of faults you're seeing, a multimeter won't do any good.
What I think you're seeing here is a poor connection at the relay lugs (where they plug into the socket). A very thin oxide layer builds up on the leads or socket connections. For high current connections (such as the ABS pump), very little resistance (a few ohms) can be enough to reduce the current to the pump and keep it from starting. With a meter, you aren't going to see the ohm or two difference.
The other issue with relays, especially those mounted under-hood, is that the solder contacts internal to the relay develop micro-cracks. This is from the heat and vibration. These cracks usually form on the large pads on the circuit boards, because they also provide mechanical mounting for the heavy relays. The solution is to re-flow the solder joints. Or replace the relay. I like reflowing, because (1) I'm cheap, and (2) I have the equipment and experience.
Clean the relay lugs with some Scotchbrite. A little fine sandpaper will work, too, just very gently - you don't want to remove the plating on the leads.
The ABS sensors have connectors up in the aquarium area on the left hand side at the base of the window. They are a set of two-pin connectors. Sometimes just reseating the connectors works well. With the sensors, you can measure the resistor resistance with a meter. I don't remember the exact value of 'good' or 'bad'. I think it's on the order of 2K ohms. The trick is to measure all of the senosors, and see if one is significantly different than the others.
posted by 192.249....
, Wed, 5 May 2004 06:58:32 <-- Viewing This Message
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