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Old Nov 9, 2008 | 09:39 AM
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I'm simplifying a harness and came across this little resister (pic 1, 2) or something between two injector clips. It has 1.5A stamped on it. It is not attached to the injector clips, just situated between them. This is from an Auto '04 GTO harness. One wire (black w/red) goes into a ground junction with a couple other wires then into the first sensor plug in pic 3. The other wire (green) goes to a junction with 3 other green wires. The sensor plug has another wire going into it which is green. If I could identify the sensor plug, that might help.

Any idea what it is? Sorry for the crappy pictures.

Also, if anyone can find the thread of an f-body harness laid on a piece of plywood with the sensors labeled, that would be great help. I can't find it.

Thanks,
Frank
Attached Thumbnails harness question-resistor1.jpg   harness question-resistor2.jpg   harness question-plug.jpg  
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Old Nov 9, 2008 | 10:11 AM
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One for the archives. The plug is for the AC compressor. Not sure what the little resistor is for, but I'll be deleting it all.

Frank
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Old Nov 9, 2008 | 10:15 AM
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I was thinking that was what it was, but I couldn't see the plug very well in the picture, between the fuzziness and my old age. It isn't a resister, its a diode to protect the PCM from the collapsing electrical field in the clutch coil. This back EMF can burn out the output driver in the PCM.
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Old Nov 9, 2008 | 11:50 AM
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I coudn't find that pic, but here is one that I made for my Car and labeled it. It's not blown up, but you get the idea of the essential stuff..
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Old Nov 9, 2008 | 12:20 PM
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Originally Posted by poconojoe
I was thinking that was what it was, but I couldn't see the plug very well in the picture, between the fuzziness and my old age. It isn't a resister, its a diode to protect the PCM from the collapsing electrical field in the clutch coil. This back EMF can burn out the output driver in the PCM.
he is right. it is a clamping diode for the a/c compressor coil.
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Old Nov 9, 2008 | 01:33 PM
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Does anyone know the specs on the Diode?
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Old Nov 9, 2008 | 01:50 PM
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I replace them with 1N4004 They're only rated for 1 amp instead of the 1.5 amps the factory one is rated at, but its good for 400 volts, and I've seen much lighter duty ones used for the same purpose . Plus you can buy them at Radio Shack for about a buck for 2 of them. If you put it in backwards, it will blow your A/C fuse
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Old Nov 10, 2008 | 04:47 PM
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Thanks Merv. That'll work fine.

And thanks for correcting my non-electronics ***.

Frank
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Old Nov 10, 2008 | 05:34 PM
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Here is the link to the f-Body six speed harness.

https://ls1tech.com/forums/conversio...ification.html
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Old Jun 22, 2010 | 02:33 PM
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Originally Posted by poconojoe
I replace them with 1N4004 They're only rated for 1 amp instead of the 1.5 amps the factory one is rated at, but its good for 400 volts, and I've seen much lighter duty ones used for the same purpose . Plus you can buy them at Radio Shack for about a buck for 2 of them. If you put it in backwards, it will blow your A/C fuse

Bumping this up-

Doesn't the OEM relay have a diode in it? If so, does 85 or 86 go to the PCM? I cannot find schematics on it.

If it does not, can someone remind me how to wire in a diode? Its been awhile since I've had an electronics class...... about 4 years
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Old Jun 22, 2010 | 02:52 PM
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Lightbulb Reality check..

When I got my harness, [aftermkt], I made up a test for it, and the sensors.
I took the engine, and trans, [both on stands], and hooked up a ground between them. [Jumper cables].
I plugged in all the sensors, the t/b, trans, pnp switch, injs, coils...everything.
I made a "key sw" out of a on/off toggle, connected it to the fuse panel, ran the - side of the jumper cables to the engine, w/ a battery on the floor.
I have EFILIVE, so I plugged it up, and booted it.
Once set, I "fired the engine", read all the sensors, tried the DBW. Everything checked out.
All told, took me 30 minutes...
This way, I hope to be able to install everything, and not have to troubleshoot problems while crammed under the dash, hanging over the fender, etc...

Food for thot... ESPECIALLY w/ modded stock harnesses.
[Think how many fewer threads there would be about mismatched DBW components, incompatible sensors, etc, if this were done more frequently..] I'll trade 30 mins for 4 days of aggravation any time!
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