03 V8: Transmission lets go, slams back into gear

[MikeinNH67]

That's a very informative video for those of us that haven't hit this problem...yet. Ticking time bomb with corrosion and makes a strong argument to unplug the transmission connectors and protect the pins with appropriate corrosion inhibitor. The connectors are sprayed with water (and salt in many cases) such that even the seals can't prevent this outcome.

Spring maintenance project queued up! Thanks Sarge. Can of DeoxIT D5 ordered, and I'll apply my usual thin coat of dielectric grease along the weatherproof seal during reassembly.

It's funny that I had just watched that video right before I saw and posted it to this thread earlier. I like the Youtuber's videos and he happens to own a 4runner.

As for touching these connectors once a year, I'm not sure that would be helpful or possibly break them quicker. They look pretty fragile. Could do more harm than good.

 

[waypoint]

As for touching these connectors once a year, I'm not sure that would be helpful or possibly break them quicker. They look pretty fragile. Could do more harm than good.

Agreed, this is a one and done maintenance item.

 

[Sdurza]

I had a 2006 Tacoma that did this constantly, never could figure out why. Drove it well over 300,000 miles.

I have recently noticed that my 2007 4Runner does the same thing, I doon't think it is causing any harm though.

 

[Montego Murph]

I had a 2006 Tacoma that did this constantly, never could figure out why. Drove it well over 300,000 miles.

I have recently noticed that my 2007 4Runner does the same thing, I doon't think it is causing any harm though.

I don't think we're talking about the same thing here. This is a really violent slam... visualize pulling the shift into drive at 2000 RPM.

 

[Sdurza]

I don't think we're talking about the same thing here. This is a really violent slam... visualize pulling the shift into drive at 2000 RPM.

Yikes, mine only happened if I was coming to a stop after got 60+, adn it had to be a complete stop. It almost felt as if I got rear-ended. My 4runner has done this to me as well, if you figure out what it is please let me know!

Thanks!

 

[Montego Murph]

March 20 Followup

OK... Time for a followup to this mystery.

Last time I checked in, Toyota told me that the solution was to just replace the whole transmission.

Friend of a friend owns a mobile diagnostic shop. It was recommended to have him check out the wiring and somehow determine what exactly the problem is. Left the truck at his shop so the diagnostics guy could investigate.

Diagnostics guy said he had nothing to work from since the Toyota techs cleared out all the codes. Several attempts at driving the truck would not show problems or throw codes, so I took the truck back to my place with the idea that I'd drive it until it trips the code, then bring it back for diagnosis.

It's driving perfectly. No trips, no slams, nothing. Just the TRAC/SLIP combo which came on with the CEL a few weeks ago. A quick ZPC will take care of that. Good thing I have a Zero Hero!

I have a theory which is lining up in my head pretty well.

When the truck was at Toyota, I asked them to check that one wiring connector we've been discussing. I was told that there was minor corrosion but nothing to be too concerned about.

I think that the "minor corrosion" was enough to cause occasional resistance which then triggered the issues that started this whole thread. When they pulled and inspected the connection then reconnected it, I wager that action scrubbed off enough corrosion to "fix" the issue. Maybe I should say "postpone the problem."

I have only local travel for the rest of the week, so I'm going to drive it as much as possible and see what happens. If the problems have indeed been resolved and I'm not able to generate a code or make it stumble-shift, it sounds like the Deox-IT treatment that Sarge suggested would be a wise next step along with fortifying the rubber seal. That stuff is pricey, but much more affordable than a transmission. One thing I've learned is that good tools cost good money.

Until my next follow-up...

 

[waypoint]

I think that the "minor corrosion" was enough to cause occasional resistance which then triggered the issues that started this whole thread. When they pulled and inspected the connection then reconnected it, I wager that action scrubbed off enough corrosion to "fix" the issue. Maybe I should say "postpone the problem."

This is good data, thanks for updating us. Not the first time I've seen fouled electrical connections cause transient problems...I once fixed a fuel pump failure just by removing and cleaning the fuse in the under-hood box.

Next oil change I'll be disconnecting, cleaning, and applying DeoxIT compound on mine.

 

[Sarge]

Glad to hear some closure of sorts - those connectors are quite sensitive and use some pretty small pins. From further reading on that transmission and the ECU that runs the thing, it seems like this wiring problem is cropping up more often. The amount of road salt chemicals used in Illinois sure doesn't help - on quiet nights you can hear all the Chevy's rusting off their frames in this state.

The DeOxit isn't cheap by any means - but it actually works and does exactly what it is stated in their literature, which is truly rare. The real problem is a lack of space and the location of that plug - I do wonder if the job as a whole would be easier if the harnesses were replaced and some preventative measures are taken when installing them. Trying to get a decent look down inside that female portion on the transmission is a feat in itself.

Sarge

 

[Montego Murph]

The real problem is a lack of space and the location of that plug - I do wonder if the job as a whole would be easier if the harnesses were replaced and some preventative measures are taken when installing them. Trying to get a decent look down inside that female portion on the transmission is a feat in itself.

I would agree with you fully if replacing one of those harnesses didn't mean dropping the trans pan and valve body, but that might be the only way to access the plugs to do the job properly (other than cutting a hole in the tunnel.)

I was looking at the different Deoxit compounds available. Do you recommend using the spray, or liquid/brush? I wonder if I could get hold of a small camera (like an old go-pro) up above the plug and use that like an electronic periscope of sorts.

 

[Sarge]

It depends on the level of corrosion. Due to the size of the pins and the fact that these signals are read by the ECU - I would not use the D-100 full-blown cleaner. Probably just stick with the DeOxit D5 since it has a great protectant in it. There is also Lithium-based spray grease protectant, but that would be mostly for trailer plugs and such things. If you have questions about their products - they have a technical email link. Caig Industries has some great techs that can help you figure out what to use for the given situation.

Help Learn - CAIG

My '03 has slowly been showing signs of some issues when first driven with shifting quality/sluggishness lately - I suspect either a fluid flush/fill or a need to clean that stupid plug is in order soon.

Sarge

 

[Montego Murph]

Probably just stick with the DeOxit D5 since it has a great protectant in it. Caig Industries has some great techs that can help you figure out what to use for the given situation.

Help Learn - CAIG

Sarge

Hey Sarge,
I've got questions as I navigate their self-help screen, and would likely have the same questions if I called the hotline so I wanna ask here first. I figured I'd ask here so others can benefit from the knowledge.

It doesn't seem like flammable/nonflammable is an issue. I mean, I don't want it to catch on fire, but there are no sources of open flame or spark while I'm doing the job. There is that rather large heat source, but I'd think this will have evaporated long before I start it up.

It looks like I want the D5s-6n spray with the quick-dry non drip solvent so it sticks to the connectors and protects longer. Would you agree?

I'll make you a deal... you help me pick the product, and I'll bring it up there for you to use on wrenching day!

 

[Sarge]

Any of the D5 series is basically the same - the non-drip can contain fewer ounces of the product is the only difference. You're paying more because of the can per ounce - so the regular D5 @$19.95 is a better value.

I got a sample of their precision Lithium Grease compound with no particles and infused with the D-100 cleaner - it is a temporary sample offer here...
Grease free sample from CAIG Labs

It would be great if that pair of plugs could be coated with this grease - but again, the location of them makes that nearly impossible unless you hack the tunnel or remove the harness altogether for access.

If you go back and watch that video, those type of pins in that plug look like the typical 1.3mm straight pins - which are really fragile. I wonder if trying to clean the dumb things is a waste of time and may more likely result in having no choice but to replace the harness - at least the female end, which is in the transmission itself, behind the valve body. At that point, the lithium grease would be a great protectant and should last the life of the driveline from that point. For vehicles that have already shown a harness problem - I would suspect that is the only ultimate solution since the corrosion can cause so much damage to such a fragile plug. The guy in the video had to drill new pins into the thing to make contact possible, at best a sort of hack. I would bet that long term that will not work, at least for very long.

I can still do some topside work, but my days of working under a vehicle for any length of time are over - too much damage to my spine.

Sarge

 

[maxs4runner]

So I gather it was just a matter of unplugging the harness on the passenger side of transmission and cleaning corrosion and then adding a electronic cleaner/protectant? I am getting a different specific code for the SLT solenoid D pressure valve. This would be a much cheaper fix haha

 

[Montego Murph]

I wonder if trying to clean the dumb things is a waste of time and may more likely result in having no choice but to replace the harness - at least the female end, which is in the transmission itself, behind the valve body. At that point, the lithium grease would be a great protectant and should last the life of the driveline from that point.

Is the idea here that the cleaner is somewhat acidic by design (to "eat" the corrision) and might destroy the pin in the process if the corrosion is bad enough?

I did get hold of an old GoPro camera. I'm wondering if I could get it up in the transmission tunnel and use it like a periscope and do the work as if I were operating a puppet show. I'm due for an oil change soon so I may reach up there and see what the space situation is -- like could I even fit my hands up there?

I don't think replacing the internal harness would be too horrible. Messy as hell, but I don't think I'm afraid of the job. I had to replace some solenoids on a Grand Cherokee transmission a few years ago and that was successful, so I think this would be about the same. I probably still have ATF in my hair from that job.

 

[maxs4runner]

Do a quick search on Amazon for inspection camera... You can get a camera on a 4' flexible cord which connects to your phone for about $20. Works great for checking things in tight spots

 

[Sarge]

De-Oxit does as its name implies - it removes the oxide layer that has formed on connectors, that is all. Not an aggressive acid as some that require a second neutralizing solution. What I'm getting at is the mechanical strength of those pins in the plug - they are very small and fragile. Go back and watch the video - there is little metal there to work with and unless that set of pins is only lightly corroded I would say the harness has to be replaced or the problem is going to come back.

YouTube

Sarge

 

[earthrealm]

Is the idea here that the cleaner is somewhat acidic by design (to "eat" the corrision) and might destroy the pin in the process if the corrosion is bad enough?

I did get hold of an old GoPro camera. I'm wondering if I could get it up in the transmission tunnel and use it like a periscope and do the work as if I were operating a puppet show. I'm due for an oil change soon so I may reach up there and see what the space situation is -- like could I even fit my hands up there?

I don't think replacing the internal harness would be too horrible. Messy as hell, but I don't think I'm afraid of the job. I had to replace some solenoids on a Grand Cherokee transmission a few years ago and that was successful, so I think this would be about the same. I probably still have ATF in my hair from that job.

So how did the ops go?.
Am having a somewhat similar issue. Though mine is p0977 - shift solenoid b control circuit high, probablly high resistance due to corrosion. Was unable to even unplug the harness.

The youtube video in the link has given me pointers on how to tackle the harness unplugging.may likely cut a window in the transmission tunnel.