Relay Test?

DByers · 10-11-2002, 10:55 AM

Is there a way to test the round 5 pin relay to be sure if its good with an ohm meter? What should the values be from pin to pin?
TIA

RoninLB · 10-11-2002, 11:05 AM

being some what simple minded I'd do a voltage drop under load to test contacts..assuming it triggers..............Ron

HawgRyder · HawgRyder's Garage

Grab your battery charger and put the output across the coil terminals to see if the beast "clicks".
At the same time have an ohmeter across the output and input terminals to check the resistance of the contacts.
Can someone translate this into terminal numbers?
Bob

911pcars · 10-11-2002, 11:42 AM

I think all Bosch relays are numbered the same. Here's an attempt at describing how a relay works (w/pin numbers) for a set of H4 headlights:

http://pub120.ezboard.com/fearly911sregistryfrm2.showMessage?topicID=334.top ic

In part:
"Terminals 85 and 86 make up the control circuit. Terminals 87 and 30 make up the power or contact circuit. When current goes through 85/86, the control circuit is energized or electromagnetized (there's a coil of wire between 85 and 86 inside the relay housing). This causes electrical contacts inside to close and connect 87 and 30."

Hope this helps,
Sherwood Lee
http://members.rennlist.org/911pcars

makaio · 10-11-2002, 12:06 PM

A mechanic friend of mine once told me to test the round relay's, like the one in your picture, remove the horn relay, and insert the relay to test. If the horn works, its good. If the horn doesn't work, its bad.

DByers · 10-11-2002, 12:13 PM

Thanks guys. Just trying to track down a few gremlins.
Makaio, tried that but unless there is a relay hidden somewhere in the 4th dimension of my car that I am missing my horn works no matter what. Relay in relay out. Only time it doesnt work is when the battery is disconnected. I know there has got to be a relay for the horn somewhere, just cant seem to find it. One of the gremlins I am tracking down.

RoninLB · 10-11-2002, 01:57 PM

Dan...do you have your horn relay tucked well behind the left battery..or maybe it was only '69/'70.................Ron

DByers · 10-11-2002, 02:38 PM

Ron, From what everyone tells me and the wiring diagrams, the relay next to the front left battery by the fuse panels is the horn relay. Horn works with it in or out. Same relay in the engine compartment (cold start relay?) and the one behind the gauges also do nothing. Hell I have removed all these relays and started and ran the car around the block, put them back in and same deal. The gremlins have to do with the hazards and turn signals. All grounds are clean and tight. Not a big deal since she drives and has headlights and bracklights. That turn signal thread got me thinking though that I should fix that problem. Going by my Dads house this weekend to use his tracing tool to track down some wires.

RoninLB · 10-11-2002, 03:11 PM

Dan..I'm not clear on the problem..but sounds like someone rewired the horn/trace the wires..if you have a short . there is a $35 short finder..you replace the fuse with one part of the gizmo and trace along outside of wires/bundle with some kind of direction finder..............Ron

DByers · 10-11-2002, 03:24 PM

Thanks Ron. I not sure of the problem either. My blinkers and hazards were not working but since I havent had her on the road that long since bringing her back to life, I wasnt worried about it. Then I saw the thread on using turn signals and thought how I should really fix the problem. Figuered simple relay fix. So I start searching for the relay. In short car runs great and everything works (except blinkers/haz) with or without any or all relays I can find and pull. So now I am going to have to trace and ring the wiring just to give me peace. At least that is just time and not alot of $$$.