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MAGNUM S/T
Dodge Dakota
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6/05/2003
07:41:14
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 Subject: How to check a switch using ohm meter
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Message:
I wanted to check my reverse light switch to make sure the wiring is good....right now I have no reverse lights.
What's the best way for me to use an oHm meter to check the wiring? Essentially there is a connector that I can uncouple....but then I don't know exactly how I can use my meter to see if the switch...and/or the wiring for the switch are working. Do I need to remove the switch from the tranny entirely to cehck it??
Any help is appreciated. I found out today that a replacement switch is $87...so it's worth me doing a little self diagnostic first.
TIA
Kevin
http://webpages.charter.net/khoegen
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Dragon
Dodge Dakota
JOIN HERE
6/05/2003
08:11:15
|  RE: How to check a switch using ohm meter
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Message:
Pull the connector off the switch. Connect one lead of the ohm meter to one leg of the switch, the other lead to the other leg of the switch.
Make sure there are blocks behind the wheels so the truck doesn't roll.
Also make sure the resistance setting on the ohm meter is close to what the switch is rated for. You don't want the meter pushing more voltage or amperage through the switch than it is rated for.
Place the truck in reverse and see if the ohm meter reads near or at zero, indicating little or no resistance. This would indicated that the switch is allowing current in this position.
If the meter reads infinity (the sideways 8), or a high level of resistance, then the switch is bad and will have to be replaced.
Hope this helps.
Michael
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MAGNUM S/T
Dodge Dakota
JOIN HERE
6/05/2003
08:25:04
| RE: How to check a switch using ohm meter
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Message:
Michael,
I appreciate the reply. If I understand you correctly, essentailly I want to see two significantly different readings when comparing tranny in reverse and not in reverse? Is this what is referred to as a 'continuity' check?
Also, can I do the same with the other end of the connection (the wire connector that the switch plugs into), in case there is a bad connection there? Or does that require a different technique?
Thanks again, you've been alot of help
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MAGNUM S/T
Dodge Dakota
JOIN HERE
6/05/2003
08:52:08
| RE: How to check a switch using ohm meter
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Message:
Michael,
I appreciate the reply. If I understand you correctly, essentailly I want to see two significantly different readings when comparing tranny in reverse and not in reverse? Is this what is referred to as a 'continuity' check?
Also, can I do the same with the other end of the connection (the wire connector that the switch plugs into), in case there is a bad connection there? Or does that require a different technique?
Thanks again, you've been alot of help
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02Sport+
Dodge Dakota
JOIN HERE
6/05/2003
11:00:56
| RE: How to check a switch using ohm meter
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Message:
Check the switch as Magnum ST replied, with the meter leads hooked up to the 2 switch leads. Put the truck in reverse, and note the reading on the meter. It doesn't make any difference what resistance setting you choose, you'll get a more accurate reading on the lowest setting, such as 0 to 200 ohms on your meter. The current that's supplied from an ohmmeter will not hurt a switch. Take the truck out of reverse, and see if the resistance reading on the meter is opposite of what you just checked (either 0 ohms or infinity. Infinity indicates an open circuit...you're checking to see if the switch contacts are closing and opening properly). If it does, the switch is OK. If you have 0 ohms or infinity ohms in both cases (reverse and out of reverse), the switch is likely bad.
You would probably not be able to check the wires in the connector that's plugged onto the switch, as those are the wires that carry either the voltage or a ground to the PCM, or whatever else looks at the reverse switch signal, and the other end of the wire is probably a long distance from the switch end. Inspect the connector and the wires going into it for corrosion or breaks. Failures usually occur at the connection points, or very close to them, like at a bend.
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02Sport+
Dodge Dakota
JOIN HERE
6/05/2003
11:03:01
| RE: How to check a switch using ohm meter
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Message:
Oops, meant to say check the switch as Dragon replied. Want to give credit where credit is due. :-)
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MAGNUM S/T
Dodge Dakota
JOIN HERE
6/05/2003
15:43:03
| RE: How to check a switch using ohm meter
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Message:
SEE THREAD ON 06/05/2003 IN GENERAL DISCUSSION WITH THE SUBJECT LINE: No back-up lights - resolved!!
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