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I see. The code on the valve connector is 5D. The part number is ABV00031.
The diode actually did arrive this evening and I put it in (and ran the vehicle). I'll pull it tomorrow and connect the red wire directly to the white wire, along with the grey wire that comes from the ECM eliminating the new diode I purchased. Right?
Steve
Put it back like it was before you put the diode in......!!
I'm just trying to understand. And it doesn't make sense to me. But, I'll hide and watch.
Lol, lol, lol, lol.......... This story gets better and better every day. I will never forget this thread, or Steve......
I'm going get that beer someday.... 75 post related to this Diode story.
These 75 post are going to end with the story that there is actually nothing wrong with the current diode wiring except for the wire-nut, and the other red wire was not folded and taped over.
But, I learned a few things and lessons along this thread......
And the story is not over lads, we just need a rainy day in PA………
Gary, sit back and enjoy the ride....
Last edited by vjsimone; Jul 20, 2016 at 11:52 PM.
Reason: Adding text
OK friends. I'm getting two different points of view here from two very capable mentors. Gary indicates there shouldn't be a problem leaving the new diode in place. Vince says to get rid of the diode I installed. Which way do I go?
I ran it last evening after putting in the diode and took about a 10 mile run. It ran fine. The only thing I noticed was a momentary significant drop in RPM's when shifting from park into drive. Then it stabilized.
Park RPM's are at 720. Drive RPM's are at 570. Shifting takes the RPM's down to 300 (thereabouts) for a second then stabilizes. Could it be the diode I installed? Vincent says he had read that the diode I installed will mess with the idle. In the case I described, he seems to be correct.
If I pull the diode, it seems to me the unconnected red wire (The one I presently have running into the diode along with the other wire that connects to the white wire on the IAC connector) should be connected to the white wire to the connector along with the other wire. But Vincent says to put things back the way I had it. Does that mean that I should leave the other red wire disconnected?
Steve
Originally Posted by Gary Lewis
I'm just trying to understand. And it doesn't make sense to me. But, I'll hide and watch.
I'm sorry to have confused things. I was really asking Vic why two diodes would cause a problem, not suggesting you leave it in. Vic is the guru here, so do what he says.
As I noted before the purpose of the diode is to keep the IAC valves solenoid from ringing.
Doing away with the rigging makes the IAC valve respond faster to the commands of the EEC Computer.
Without the diode the valve response would move slower when the ECC wants to close the valve.
I do not have the old IAC. I have a new one installed and a spare new one because I ordered two thinking the first new one wasn't working correctly.
I understand what you are saying about the function of the diode. Still, I need to know what to do with the other red wire. Connect it to the white wire extending from the connector, or leave it unconnected?
I do not have the old IAC. I have a new one installed and a spare new one because I ordered two thinking the first new one was working correctly.
I understand what you are saying about the function of the diode. Still, I need to know what to do with the other red wire. Connect it to the white wire extending from the connector, or leave it unconnected?
The Red wire is now a spare. I suggest you fold an inch of it over and tape it up.
I believe your truck was modified correctly by the previous owner when he replaced the IAC. I guess you found the red wire when you were re-attaching your wire harness after your rebuild.
Leaving 2 diodes in the circuit, may cause an erratic idle from what I have read.
I have had an epiphany here myself, last night I realized after the research, the surge at Idle I am having and cannot figure out, is due to the new IAC, and 2 diodes in the circuit. I will be cutting that diode out of the circuit this weekend.
As I noted before the purpose of the diode is to keep the IAC valves solenoid from ringing.
Doing away with the rigging makes the IAC valve respond faster to the commands of the EEC Computer.
Without the diode the valve response would move slower when the ECC wants to close the valve.
subford, I am not suggesting he operate without a diode, for it is reported that without the diode, damage may occur to the EAC.
Steve has reported that his new IAC is a replacement with the diode installed.
Steve formally reported his idle was great. After adding the second diode, he reports some anomalies with his idle.
Vic - Please repot back on the results when you cut one diode out. I ask because I cannot figure out how two diodes could cause a problem. Whichever diode switches on fastest will conduct the back EMF from the solenoid. The other one may switch on and help, but we are talking about such small differences in current that just a different diode would make bigger changes.
Given that, I don't think you will see a difference. But, I'm here to learn so please let us know.
Yes, Vincent. Clarification for you. I do not intend to use the second diode. In fact, I have already removed it. But, the second red wire was originally connected to the side with the white wire. Still disregard it? I will do what you recommend.
Originally Posted by vjsimone
The Red wire is now a spare. I suggest you fold an inch of it over and tape it up.
I believe your truck was modified correctly by the previous owner when he replaced the IAC. I guess you found the red wire when you were re-attaching your wire harness after your rebuild.
Leaving 2 diodes in the circuit, may cause an erratic idle from what I have read.
I have had an epiphany here myself, last night I realized after the research, the surge at Idle I am having and cannot figure out, is due to the new IAC, and 2 diodes in the circuit. I will be cutting that diode out of the circuit this weekend.
The Red wire is now a spare. I suggest you fold an inch of it over and tape it up.
I believe your truck was modified correctly by the previous owner when he replaced the IAC. I guess you found the red wire when you were re-attaching your wire harness after your rebuild.
Leaving 2 diodes in the circuit, may cause an erratic idle from what I have read.
I have had an epiphany here myself, last night I realized after the research, the surge at Idle I am having and cannot figure out, is due to the new IAC, and 2 diodes in the circuit. I will be cutting that diode out of the circuit this weekend.
I'm just trying to understand. And it doesn't make sense to me. But, I'll hide and watch.
There would be a voltage drop across each diode, so slightly less voltage would show up at the ECM (if I got my directions right). When the computer activates the FET to ground the IAC it should still work the same way, I would think.
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