buzzing transmission solenoid

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dnewton3

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Arrrrrrrrrggggggghhhhhhhhhhh .....
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Having a problem with my 1995 Villager tranny. I've searched and not found any info here specific to my concern, so I'll take any sane advice, and possibly insane, at this point.

History:
1995 Villager with 242k miles on it. Has had a flawless tranny up to this point. In fact, it still drives and shifts fine even now. Last week I had to remove the upper intake manifold to replace the fuel injectors on the back cylinder bank. Other than normal lube and filter service, the tranny has needed nothing. Even have a UOA from the tranny; totally fine.

Let me give you the sequence of what I did, so it will make some sense:
Engine begins to run rough last week, says the wife and kids.
Replace plugs - no change.
Replace plug wires - no change.
Test front bank fuel injectors; one has high impedance; out of spec.
Need to test rear bank injectors; remove upper intake.
Find one bad injector in back as well; replace all three because it is a flaming PITB to get to them, so I only want to do this once ...
Put all back together; engine will not idle correctly and has a cyclical up/down rpm action from 1500-2500 rpm; will continue this until you give some throttle, and then rev's immediately to 3000prm.
Start testing all possible sensors and such; TPS, IAC, FIC, BPA, etc. Finally notice that the cruise control is actually making it run high; seems to be inadverently actuating; so I disconnect it. Now, it runs and idles normally.
But when I was testing some of the electronic controls, I hear this clear and distinct "buzzing" coming from the tranny area. It's not hydraulic; the engine is not running. The noise is most certainly a buzzing as if there is an electronic aggitation.
Suspect the NSS (neutral safety switch; aka range sensor); check it by the manual and is fine. I remove it from the mounting location but leave it connected, and can still hear buzzing coming from down low, while the NSS is in my hand; cannot be the NSS.
Trace down the wire loom running into the tranny that has to be the electronic solenoid actuactors for shifting inside the tranny.
I can make the buzzing stop by unplugging the connector, so at this point I'm fairly sure it's the solenoid pack for the internal tranny works.

The story does not stop there, however ...
The buzzing ONLY happens when NOT at idle. When the engine is not running, but the ignition is "on", and the throttle is closed, there is no buzzing. But when you lightly open the throttle (hand rotating the throttle drum where the cables connect), the buzzing starts. This is (presumably) because once you open the throttle, you break the connection in the switch. Most folks don't know that there are often TWO electronic pieces in a TPS (throttle position sensor); one is a potentiometer that varies resistance, the other is a simple switch that is closed/opened upon throttle movement. The former is what the ECM uses to determine fuel injector rates, while the later is used as part of the start-safety routine. I'll be honest and say that I cannot remember at this very moment if the switch is NO or NC, because I've tested so many items over the last three days that my memory is fuzzy at this point. But what I can tell you that it checked fine by the manaual procedure and specs, and even was duplicated in results when I tested it against a brand-new one right out of the box. So, what is happening is that when the throttle plate in my van is closed, there is no buzzing, but as soon as you open the throttle, and manipulate the TPS safety switch, the tranny solenoid starts buzzing.

So, I think I have a good idea of WHAT is causing the noise; it's the tranny solenoid. But the underlying question is WHY is it making this noise?

I have a few thoughts here, and this is where I could use some BITOG input if anyone has had experience with a similar issue.
- the ECM could be going bad, and sending errant voltage to the solenoid.
- the solenoid itself could be going bad
- the alternator could be bad; the rectifier may be failing and leaking AC into what I presume should be a DC circuit
- main wiring harness could have a bad connection

As for those three things, here's the issue with each:
- replacement ECMs are availble, but not cheap. Hard to do because it's burried up under the dash
- tranny solenoid is available, but not cheap. Never replaced one before; looks as though I could accomplish it, but with a lot of time consumption. However, I am making a LOT of presumptions here. I assume I can drop the pan, disconnect the solenoid, and then pull the harness through the case hole?
- alternator is the easiest to replace, and not too expensive. The voltage is rock steady, and since everything else in the van works fine, I doubt the rectifier (which is inside the alternator) is bad
- wiring harness is very hard to troubleshoot; wrapped tight, and very hard to get to, and also no aftermarket replacement available (not yet checked on OEM replacment, but I'm sure it would be VERY expensive, if so). To replace this is a major undertaking; lot's of stuff has to come off because some of it is under the intake

I don't want to just spend money on replacement components in a guessing game. Let's face it; the van isn't worth much. I'm not going to throw $1000 into it and "hope" that I have "guessed" which part is bad. I do not mind spending money on a good fix; that does not bother me at all. What concerns me is spending money on a SWAG, and throwing money away.

Now, believe it or nor, the van still drives fine. It shifts normally, makes no odd sounds (other than the buzzing upon open throttle). There are no leaks or any other tell-tale sign of problems. Part of me thinks I should just let her drive it, and it will fail when it fails. But that is typically not my nature; I try to be pro-active and fix stuff before it fails, or at least address it as soon as it fails. Knowing something is wrong, and doing nothing about it, just eats away at me in no uncertain manner.


I'll take advice please!
 
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i don't know whats normal for a villager?
-but early a604 solenoids would make a buzzing sound, and were very noisy.
 
I take it that this change came about directly after removing the intake and replacing the injectors?

Double check that you've got all the connectors back in their correct spots. Some of the imports (You have a Nissan Quest I believe) have duplicate electrical connectors. That can make weird things go on from time to time.

I certainly wouldn't advise replacing anything yet, since the reading suggests that it was fine before you started the project.

edit: Since you can repeat the buzzing with the engine off, try unplugging one sensor or injector at a time and testing by opening the throttle. Maybe you can catch it and narrow it down that way. Also inspect for a damaged wire harness. Not just by your doing either. Sometimes they'll get oil soaked and the insulation will come apart and wires will short. Other times there's mechanical damage- like a short to ground or short to power.
 
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I agree with The Eric, if the tranny was working fine before you worked on the motor, chances are you did something (not on purpose) that is affecting your tranny now. Before you start swapping parts, check to make sure everything is back in place properly.

You did mention you disconnected your cruise control because after you worked on the motor, the cruise messed up the idle. That's where I would concentrate and try to figure out the problem there as my guess is the two are related.
 
I'm with GreeCguy.

Very odd that the cruise would impact idle. something's not quite right.

Is there a ground dropped somewhere?

Is there any potential voltage measured from engine frame to vehicle chassis to battery (-)?

It's not the alternator.

Does the ECU need to learn the new injectors? Do you need to do an ECU reset?

Is it possible this has been going on for a while and wasn't noticed?

I wouldn't be surprised if it's the solenoid that drives TC lockup.... it will either be off, partial (via pulsed signal) or full-- to drive lockup. It may go into a standby condition where it sees like a 1-5% duty cycle, which is what you would hear--- where it's energized but not with enough duty cycle to actually move. Just guessing--- as this might not be anything to worry about.

In some vehicles I've owned, I could here electronic "whining" under the hood if the key is on but the engine not running, for as long as it stayed that way (not the fuel pump).

Drive it. see if it's reliable. check your work.

good luck!
 
First off, you don't pull the shift solenoid wiring through the hole in the transmission for the wiring. It has it's own disconnect plug in the transmission. You should unplug the wiring harness connector to the transmission and manually test the solenoids. You ohm them out and the resistance should be within specs, as per the factory service manual tests. Then you can apply +12V to the solenoids individually to see if they click. I suspect that you might have a piece of dirt in a bad spot in the transmission, or a bad piece of wire, or bad solenoid.

In so far as pricing try
http://www.transmissionpartsusa.com/

or eBay.

Check for codes! A transmission solenoid problem won't light your dash light. You need to use your code reader, of if this car is EEC-IV like my 1995 Escort (it probably is) then all you need is a short piece of wire and and some patience and practice.

I am about to replace a solenoid in my 1995 Escort at over 215K miles I do have a bad one. Doesn't make any noise, but I am driving in limp home mode (factory service manual calls it "minimum drivability mode").
 
Sounds normal. Could be a solenoid being applied in response to the TPS voltage changing with KOEO. With KOER, sound is most likely drowned out. I would not worry unless shifting issues develop. Btw, enjoy your posts.
 
I have a sneaking suspicion that the idle and buzzing are related. It sounds (speculation follows) as if the solenoid that creates the equivalent of "throttle pressure" in the transmission is doing its job as you open the throttle... its just that it SHOULDN'T do that unless the engine is running (which masks the buzzing sound under normal circumstances).

I'm betting you rattled a wire under there when you did the repair, but I don't know which one or how you'd find it. Something related to the auto-shutdown relay that turns everything like fuel pump and ignition system off if the engine isn't running but the ignition switch is on?
 
Originally Posted By: GSCJR
Sounds normal. Could be a solenoid being applied in response to the TPS voltage changing with KOEO. With KOER, sound is most likely drowned out. I would not worry unless shifting issues develop. Btw, enjoy your posts.


This. Could be normal. Some transmission solenoids regulate line pressure through duty cycle. Ever heard an older Chrysler pulling up next to you at a light and hear it buzz momentarily as it drops line pressure to downshift seamlessly into 1st? This could be the transmission anticipating a "neutral drop" and modulating the solenoid to reduce line pressure. Why it does it when the engine is not running?


The bouncing idle usually caused by unmetered air entering manifold, in your case presumably from the cruise. The Idle bounces because the ECU is trying to control RPMs via fuel cut hysteresis since closing the IAC is not stopping a 'vacuum leak'. This is a last resort method non-DBW ECUs use to control RPMs, caused by unmetered/unexpected air entering the manifold, presumably by a cracked open throttle, or vacuum leak. I would point to the IDLE SWITCH, but I'm not going to because it seems the ECU knows when the throttle is cracked open (and starts PWMing the solenoid).... are you positive that you couldn't hear the solenoid before with KOEO and applying throttle? That just seems like a weird condition stumble across, unless you used to verify that it didn't happen before.

Overall, with a perfect mechanical reassembly, and barring abnormal operation, there could be one disconnected or bad sensor signal
 
I tend to agree, overall, that I'm the one that created the problem, during the event of taking off the upper intake.

I was diligent in replacing it, and hooking things up.

However, I'm not above mistakes, and so I went back to double check the connectors all around the area. This was also a great opportunity to teach my son troubleshooting and such, using the manual and a multimeter, etc. So I did everything twice, so that he could learn as we went.

Additionally, I once had the entire top end of this engine off before (overheated from failed water pump and wife continued to drive it ...
mad.gif
). During that rebuild, every single connector got color coded paint dots on both side of the plugs; pretty much assures the right plugs go together. All is well in that regard.

When testing all the connections on and around the upper intake (IAC, FIC, BPA, TPS, etc) everything came out fine. Checking supply voltage, reference voltages, etc, as well as testing resistance and continuity of the devices, etc.

As for the ground loop, I've checked all that as well. Check it both at the source (the cable from battery all the way down to the frame and to engine block) and also at the connectors.

I susepct that the cause is singular, and the effects are multipled. Whatever is the root cause was also effecting the cruise control, but that is a luxury we don't need, so I was able to simply disconnect it. However, the tranny solenoid is what bothers me.

BTW - here is a picture of the valve solenoid assy:
http://www.autozone.com/autozone/parts/D..._685468_0_30510
As best I can tell, there is no internal connector that would separate the valve assy from the harness. I looks to me as though the harness is made integral with all the wiring, and the whole harness would have to come out through the casing hole. Nissan does some bizare things at times.


But like I said, I'm not going to spend $330 on a valve solenoid assy, take all the time to change it out, only to find that it's not the root cause.

Against my better judgement, if I cannot get a solid lead on what might be the root cause, I'll just let her keep driving it and it if fails, we'll just scrap it
21.gif



If I had only run synthetics (oil, ATF, grease, door seal conditioner ...) this would have never happened!
crackmeup2.gif
 
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Originally Posted By: jrustles
Originally Posted By: GSCJR
Sounds normal. Could be a solenoid being applied in response to the TPS voltage changing with KOEO. With KOER, sound is most likely drowned out. I would not worry unless shifting issues develop. Btw, enjoy your posts.


This. Could be normal. Some transmission solenoids regulate line pressure through duty cycle.


This is a 1995 car, so I assume that it uses a cable instead. I'm sure that the OP knows and can report back.
 
Advance Auto parts or Autozone or Pep Boys, or NAPA aren't places where I would buy a replacement solenoid. They would charge that much for ones for my Escort and only sell me all of them at once as well. At Transmissionparts USA I can buy only what I actually need.


But like I said, I'm not going to spend $330 on a valve solenoid assy, take all the time to change it out, only to find that it's not the root cause.

If you own a voltmeter and know how to use it, you can check these with the ohms setting in your meter. If you can check sensors, you can check these solenoids.

I still think you have a bad ground, but I would be troubleshooting the cruise control to see if you find something there.

Yes it looks like on yours you don't have to open the transmission to test the solenoids directly. One of them looks separately replaceable. The other 4 looks like they come in a pack.

If you happen to need solenoids, look here:
http://www.transmissionpartsusa.com/RE4FO4A_4F20E_Transmission_solenoid_set_p/990-00099393a.htm

Shows it for $151.75 + shipping.
RE4F04A RE4F04V 4F20E Transmission Solenoid

Yes, I have bought parts from Transmissionparts USA before, and I do recommend them.
 
Originally Posted By: zzyzzx
Originally Posted By: jrustles
Originally Posted By: GSCJR
Sounds normal. Could be a solenoid being applied in response to the TPS voltage changing with KOEO. With KOER, sound is most likely drowned out. I would not worry unless shifting issues develop. Btw, enjoy your posts.


This. Could be normal. Some transmission solenoids regulate line pressure through duty cycle.


This is a 1995 car, so I assume that it uses a cable instead. I'm sure that the OP knows and can report back.


Line and other pressures regulated by VDS goes back to 1989 (Chrysler 604). By 95, many different FWD transmissions and more than a few rear-drive automatics were using VDS control systems. Odds are good that its not cable-regulated, but you may be right.
 
The tranny gear selection is by cable, running up to the front of the tranny and actuating a large selection level; kind of ol' skool. I removed the cable to remove the NSS (range selector indicator); the selection lever on the front of the tranny still has nice smooth action with full retention at the detents, so I cannot find fault here.

I've not had a chance to work on it last night; was helping a friend repack bearings, etc on his travel trailer in prep for his vacation trip. I'll try to get back into the van tonight if possible. I don't relish being out there tonight; typical hot and humid IN evening, tucked under a hood in a hot garage ... yuk.

Unfortunately, my manual does not have the data for test probing the actuator solenoids; I don't know what each lead should be in regard to terminal ID, and resistance, etc. If anyone has that data, please pass it to me.

Thanks for the link to the tranny parts place! Much better price than AZ.

I still, in my gut, believe there is a root cause elsewhere, but I cannot seem to locate it. The cruise and tranny developed the issues concurrently, so I find it hard to believe that they both went belly-up as a coincidence. I, too, believe a ground may be the issue, but for the life of me, I cannot find where it would be failing. The main chassis ground is most certianly good; everthing visually checks OK, and the rest of the vehicle operates normally, with no issues whatsoever. If this were a ground issue, it would have to be somewhere unique to the tranny shift circuitry and cruise, right? I don't see anything like that, especially in the area that I was initially working.
 
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Originally Posted By: dnewton3
The tranny gear selection is by cable, running up to the front of the tranny and actuating a large selection level; kind of ol' skool. I removed the cable to remove the NSS (range selector indicator); the selection lever on the front of the tranny still has nice smooth action with full retention at the detents, so I cannot find fault here.


One cable or two? I was referring to the cable the adjusts the transmission oil pump pressure.
 
Originally Posted By: dnewton3
Unfortunately, my manual does not have the data for test probing the actuator solenoids; I don't know what each lead should be in regard to terminal ID, and resistance, etc. If anyone has that data, please pass it to me.


Should be in the factory service manual and the schematics are in the EVTM. It is for my 1995 Escort. If you are using Chiltons or Haynes, throw them out, they are garbage.
 
I would disagree that over-the-counter manuals like Hanyes and Chilton are garbage.

After all, I used this same Chiltons manual as a guide to take the entire top end of the engine off when my wife overheated it and it cooked a head gasket. When I put it back together, it fired right up on the first crank cycle. They are not "garbage". They are also not a fully detailed troubleshooting manual; in that I would agree.

Factory manuals are much more thorough, but then again they are much more expensive. I could certainly benefit from a full factory manual at this point. I have the skills, but I need the detailed info. Which is why I posted here, hoping that someone would have direct, specific information as to which circuits to check and for what conditions and outputs.

But let's not cast such a large net of "garbage" over the Chilton and Haynes manual; they are certainly useful most of the time.


I am a DIY kind of guy. I have used those manuals to save myself literally thousands upon thousands of dollars over the years, rather than pay for for services.
 
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Originally Posted By: dnewton3
Factory manuals are much more thorough, but then again they are much more expensive. I could certainly benefit from a full factory manual at this point. I have the skills, but I need the detailed info. Which is why I posted here, hoping that someone would have direct, specific information as to which circuits to check and for what conditions and outputs.


For a 1995 car, used factory service manuals can be found cheap on eBay.
 
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