A/C Idle Up VSV works, when jumpered! Little help please...
07-09-2010, 05:57 PM
#24
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I didn't see anyone ask if qdude was getting vacuum on the valve.
The way "idle up" works is that it jumpers the throttle valve to let the engine vacuum pull in more air -- raising the idle. It is possible that the plenum (upper instake manifold) has so much gunk in it that the vacuum port to the VSV is closed. That's what happened to me. The electrical and the valve may be working fine, but the idle won't change.
The way "idle up" works is that it jumpers the throttle valve to let the engine vacuum pull in more air -- raising the idle. It is possible that the plenum (upper instake manifold) has so much gunk in it that the vacuum port to the VSV is closed. That's what happened to me. The electrical and the valve may be working fine, but the idle won't change.
07-10-2010, 07:20 AM
#25
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Scope 103;
Thanks for the post. In my situation there is no chance of being plugged up, I just did a complete rebuild and everything is super clean inside and out.
I've tried adjusting the big white bolt on the A/C idle set screw and there is no change in idle while the A/C is on. I've changed the vac lines too so I know those are clear too.
If anyone has any other ideas let me know. My solution so far has been to raise the idle so before the A/C is on the idle is high (1700) and when the A/C is on it is low (500)
Thanks for the post. In my situation there is no chance of being plugged up, I just did a complete rebuild and everything is super clean inside and out.
I've tried adjusting the big white bolt on the A/C idle set screw and there is no change in idle while the A/C is on. I've changed the vac lines too so I know those are clear too.
If anyone has any other ideas let me know. My solution so far has been to raise the idle so before the A/C is on the idle is high (1700) and when the A/C is on it is low (500)
07-10-2010, 08:28 AM
#26
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I think the ecu controls the vsv - and it's common for the ecu to switch on the ground side of the circuit - that's how it fires the injectors, for example. So if the vsv isn't getting switched, I'd say the most likely reasons are either the tps isn't grounding IDL to E2 when throttle is in idle position (closed), in which case the ecu doesn't think the throttle is at idle, hence no need for idle-up, OR, bad wiring between ecu & vsv. That's assuming one of the vsv leads has power when ignition is on.
07-10-2010, 03:19 PM
#27
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hey, seems like a common problem on a 89 and newer , that was my first post and i never did figure it out , still holding my foot on the pedal like sumone else said .hope u figure it out, good luck
07-13-2010, 02:11 AM
#28
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I'll throw in my 2 cents... I'm having the same problem with my A/C, but I have determined my problem is being caused by a faulty VSV, even though the VSV seems to be OK.
When the problem first occured, I removed the VSV, checked its resistance (47 ohms), and hooked it up to a 12-volt power supply. I heard it click, the power supply showed a current draw of 250 mA (which seems kind of high, but who knows), and the air passages were flowing and closing properly.
I reinstalled it, A/C idled up fine... On the way home it stopped working again. With the engine off (and hot), key on, A/C switch on, I unplugged the electrical connector from the VSV and re-installed it. No click, it was dead. The next morning, before starting the truck, I did the same test. VSV clicked, no problem. It worked for about 5 miles, then it stopped.
I suspect that when my VSV heats up along with the engine, it becomes unreliable. However, the next day it worked perfectly... Since then it has failed intermittently, so I ordered a new one (about 18 bucks).
My best guess is that when it heats up and the compressor cycles (turning off the VSV), that the current required to reactivate it is higher than what is normally supplied, and it just doesn't work. Another theory is that the heat causes the internals to get stuck, and only cooling down allows it to work again. My last theory is that it's just old and is no longer up to the job...
My truck has 340,000 miles, I guess I can't expect this stuff to last forever.
When the problem first occured, I removed the VSV, checked its resistance (47 ohms), and hooked it up to a 12-volt power supply. I heard it click, the power supply showed a current draw of 250 mA (which seems kind of high, but who knows), and the air passages were flowing and closing properly.
I reinstalled it, A/C idled up fine... On the way home it stopped working again. With the engine off (and hot), key on, A/C switch on, I unplugged the electrical connector from the VSV and re-installed it. No click, it was dead. The next morning, before starting the truck, I did the same test. VSV clicked, no problem. It worked for about 5 miles, then it stopped.
I suspect that when my VSV heats up along with the engine, it becomes unreliable. However, the next day it worked perfectly... Since then it has failed intermittently, so I ordered a new one (about 18 bucks).
My best guess is that when it heats up and the compressor cycles (turning off the VSV), that the current required to reactivate it is higher than what is normally supplied, and it just doesn't work. Another theory is that the heat causes the internals to get stuck, and only cooling down allows it to work again. My last theory is that it's just old and is no longer up to the job...
My truck has 340,000 miles, I guess I can't expect this stuff to last forever.
07-13-2010, 02:24 AM
#29
Registered User
Ok, spent a bit of "quality time" with my test light and VSV today. At the connector in the pic, the connector is sideways.
The "bottom" of the two terminals is constant switched 12v, regardless of whether the AC is on/engaged or not. The "top" terminal (with the end of my test light stuck in it) is strange. No power shown, and when manually grounded (with my test light) will fire off the VSV and the idle will come up some. However, when the AC engages, the test light comes on dim and the VSV fails to function. I thought this was the opposite of what was supposed to happen!!
Some electric guru needs to help my ignorant ass! I'm beggin' ya!!
The "bottom" of the two terminals is constant switched 12v, regardless of whether the AC is on/engaged or not. The "top" terminal (with the end of my test light stuck in it) is strange. No power shown, and when manually grounded (with my test light) will fire off the VSV and the idle will come up some. However, when the AC engages, the test light comes on dim and the VSV fails to function. I thought this was the opposite of what was supposed to happen!!
Some electric guru needs to help my ignorant ass! I'm beggin' ya!!
Have you tried a different VSV? Yours may just be "out of spec" and require more current than the circuit can provide to turn on.
Last edited by Bad Karma; 07-13-2010 at 02:26 AM.
07-31-2010, 03:38 PM
#32
Registered User
I got it from Toyota Parts Zone, http://www.toyotapartszone.com/genui...ota-parts.html
It solved my problem. The new VSV measured exactly the same resistance and current draw as the bad one... Just old and worn out, I guess.
It solved my problem. The new VSV measured exactly the same resistance and current draw as the bad one... Just old and worn out, I guess.
08-01-2010, 07:44 PM
#35
FWIW my local Toyota dealer quoted me $12~13 for the VSV. I ended up making my own harness from a donor plug and wired it up to the compressor power wire. So when the compressor is on, the VSV is activated/open. Working like a champ.
The problem I had was incorrect powering. With the A/C on got zero voltage at the VSV, with the A/C off, I got 4~5 volts at the VSV connector. Weird, didn't have the time nor the desire to chase an electrical problem like that. So my solution is working just fine so far.
The problem I had was incorrect powering. With the A/C on got zero voltage at the VSV, with the A/C off, I got 4~5 volts at the VSV connector. Weird, didn't have the time nor the desire to chase an electrical problem like that. So my solution is working just fine so far.
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