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testing relay?



 
 
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  #1  
Old June 29th 05, 05:41 PM
William R. Watt
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Default testing relay?


Have a horn relay. Haynes manual does not show wiring diagram.
Following is stamped on relay

GE 70
DC12V20A
N.O.
IMASEN
8J-26

One pair of contacts is marked N.O. COIL
Other pair is marked COM COIL

Any suggestion which pair is control and which is power?
Can I test with VOM (voltmeter), jumnper wires, test light?

The relay has a couple of plastic tabs on it so I might be able to remove
the cover and look inside as a last resort but am concerned about ruining
relay. It's off an '89 Festiva and the parts stores I called can't get
a replacement (at least not the parts book replacement).

Was able to remove horn and test by connecting directly to battery. Horn
works.

Tested horn circuit with test light. No light at horn end when horn button
pressed. Suspect relay. Have removed relay.





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  #2  
Old June 29th 05, 06:28 PM
Mike Romain
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Default

The coil connections are the trigger and should show some continuity
with a meter on ohms. This need 12 volts and a ground to energize the
coil and close the connection. It doesn't usually matter which is power
and ground on the coil.

The N.O. is 'normally open' and should be hooked to the horn wire.

The com is the input power from the steering column that will connect to
the N.O. when power runs through the coil.

Opening up the relay is a good idea though. You can see if the contacts
are burned or the coil looks melted.

You 'can' wire in a standard Bosch relay, but you might have to
reposition the wires. I use crimp on spade connectors to do that.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

"William R. Watt" wrote:
>
> Have a horn relay. Haynes manual does not show wiring diagram.
> Following is stamped on relay
>
> GE 70
> DC12V20A
> N.O.
> IMASEN
> 8J-26
>
> One pair of contacts is marked N.O. COIL
> Other pair is marked COM COIL
>
> Any suggestion which pair is control and which is power?
> Can I test with VOM (voltmeter), jumnper wires, test light?
>
> The relay has a couple of plastic tabs on it so I might be able to remove
> the cover and look inside as a last resort but am concerned about ruining
> relay. It's off an '89 Festiva and the parts stores I called can't get
> a replacement (at least not the parts book replacement).
>
> Was able to remove horn and test by connecting directly to battery. Horn
> works.
>
> Tested horn circuit with test light. No light at horn end when horn button
> pressed. Suspect relay. Have removed relay.
>
> --
> ------------------------------------------------------------------------------
> William R Watt National Capital FreeNet Ottawa's free community network
> homepage: www.ncf.ca/~ag384/top.htm
> warning: non-FreeNet email must have "notspam" in subject or it's returned

  #3  
Old June 29th 05, 07:50 PM
Daniel J. Stern
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Posts: n/a
Default

On Wed, 29 Jun 2005, William R. Watt wrote:

>
> Have a horn relay. Haynes manual does not show wiring diagram.


http://u225.torque.net/haynes_instructions.html

> One pair of contacts is marked N.O. COIL
> Other pair is marked COM COIL


You're misreading the markings, as it seems. I think you've actually got
two "coil" contacts, an "N.O." contact and a "COM" contact.

The two "coil" contacts are the triggers, what you are calling "control",
85 and 86 in DIN nomenclature (interchangeable since this is obviously a
relay without a suppressor diode). The "N.O." would be the contact that
goes live when power is applied across the coil (DIN 87), while the "COM"
would be the high-current power input (DIN 30).

> Can I test with VOM (voltmeter), jumnper wires, test light?


Put 12v across the two "coil" contacts and listen for a click. If you get
a click, leave 12v hooked up across the coil and use a VOM to measure the
resistance across "COM" and "N.O". It should be negligible (essentially
zero).

> concerned about ruining
> relay.


Don't worry so much about it. If you apply 12v across any combination
other than the two "coil" terminals, you won't burn anything up, it's just
that nothing will happen.

> It's off an '89 Festiva and the parts stores I called can't get
> a replacement (at least not the parts book replacement).


Exact replacement not needed. Get a standard relay (Bosch 0 332 019 151
comes to mind) and bracket (Hella 87123, for instance) and terminals
(Hella 87272). Terminals will be labelled 85, 86, 30, 87. See above for
breakout. You don't even need to buy this relay new; go hit a junkyard.

DS
  #5  
Old June 30th 05, 12:04 AM
AZ Nomad
external usenet poster
 
Posts: n/a
Default

On 29 Jun 2005 16:41:44 GMT, William R. Watt > wrote:



>Have a horn relay. Haynes manual does not show wiring diagram.
>Following is stamped on relay


> GE 70
> DC12V20A
> N.O.
> IMASEN
> 8J-26


>One pair of contacts is marked N.O. COIL
>Other pair is marked COM COIL


If you don't know the different between a coil and a contact, you have no
business doing electrical troubleshooting.
  #6  
Old June 30th 05, 01:24 AM
William R. Watt
external usenet poster
 
Posts: n/a
Default


Thanks. That was great. The relay checked out OK. The problem was a bad
circuit ground. I'll print off a copy of the diagnostic procedures for
future reference, and give a copy to the owner of the local independent
parts shop. He's good at helping people with problems and coming up
with low cost repairs.


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