Transfer Case Tuneup and Fix

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Nov 22, 2005
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Santa Cruz Mountains,CA. TLCA#7702
Hi all, Been dealing with the blinking CDL light for a while now. Sometimes it comes on with a morning start up and will go away after a short drive after turning truck off and restarting say after getting ⛽️ gas(expensive gas in CA.!!)
I have done a lot of mild dirt roads and a few rough ones and it seems with the 200 it just powers through a lot and I haven’t even engaged 4LO or EVER used the CDL in any of my modern LC’s (a 93 80(rubicon 3x definitely 4lo w double lockers engaged but never used CDL) and a 04 100) .
I think the button gets bumped getting in the truck once in a wile as we’ve had our 2014 parked by valet and get in later with the damm light blinking!! Still searching for more information for our 14 as it’s so internment.
 

radman

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Hi all, Been dealing with the blinking CDL light for a while now. Sometimes it comes on with a morning start up and will go away after a short drive after turning truck off and restarting say after getting ⛽️ gas(expensive gas in CA.!!)
I have done a lot of mild dirt roads and a few rough ones and it seems with the 200 it just powers through a lot and I haven’t even engaged 4LO or EVER used the CDL in any of my modern LC’s (a 93 80(rubicon 3x definitely 4lo w double lockers engaged but never used CDL) and a 04 100) .
I think the button gets bumped getting in the truck once in a wile as we’ve had our 2014 parked by valet and get in later with the damm light blinking!! Still searching for more information for our 14 as it’s so internment.
how old is your battery?
 
Joined
Jun 6, 2011
Messages
1,190
Hi all, Been dealing with the blinking CDL light for a while now. Sometimes it comes on with a morning start up and will go away after a short drive after turning truck off and restarting say after getting ⛽️ gas(expensive gas in CA.!!)
I have done a lot of mild dirt roads and a few rough ones and it seems with the 200 it just powers through a lot and I haven’t even engaged 4LO or EVER used the CDL in any of my modern LC’s (a 93 80(rubicon 3x definitely 4lo w double lockers engaged but never used CDL) and a 04 100) .
I think the button gets bumped getting in the truck once in a wile as we’ve had our 2014 parked by valet and get in later with the damm light blinking!! Still searching for more information for our 14 as it’s so internment.
I'd say it's time to pull the actuator and follow the procedure in this thread. I did it in both my actuators and I haven't had any blinking lights since. In my case the micro switch was badly oxidized to the point where I was getting no continuity through it and some good contact cleaner took care of it.
 

linuxgod

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Hi all, Been dealing with the blinking CDL light for a while now. Sometimes it comes on with a morning start up and will go away after a short drive after turning truck off and restarting say after getting ⛽️ gas(expensive gas in CA.!!)
I have done a lot of mild dirt roads and a few rough ones and it seems with the 200 it just powers through a lot and I haven’t even engaged 4LO or EVER used the CDL in any of my modern LC’s (a 93 80(rubicon 3x definitely 4lo w double lockers engaged but never used CDL) and a 04 100) .
I think the button gets bumped getting in the truck once in a wile as we’ve had our 2014 parked by valet and get in later with the damm light blinking!! Still searching for more information for our 14 as it’s so internment.
Doubtful the button is getting bumped. What you're experiencing is EXACTLY what many of us see (myself included). Once the transfer case warms up a bit you can restart the vehicle and the flashing will clear and the CDL will then engage.

If you've never used the CDL or 4Lo I suggest finding a dirt or gravel road or parking lot and then exercising it several times. Start with the CDL - engage it, drive for a minute, disengage it. Rinse, repeat, wipe hands on pants. Then do the same for 4Lo-4Hi. The goal is really to have the actuator move back and forth a bunch of times so that it "cleans" the electrical contacts.

As @Supra88 notes, pulling the actuator and cleaning it thoroughly is (likely) the proper fix. However if you're not mechanically inclined then you have to find a shop willing to pull it apart correctly. Many dealers won't want to try to R&R and will simply try to have you buy a replacement actuator assembly and will then drop and open the transfer case in order to swap the entire thing.
 
Joined
Aug 1, 2021
Messages
97
Location
wenatchee, WA
Doubtful the button is getting bumped. What you're experiencing is EXACTLY what many of us see (myself included). Once the transfer case warms up a bit you can restart the vehicle and the flashing will clear and the CDL will then engage.

If you've never used the CDL or 4Lo I suggest finding a dirt or gravel road or parking lot and then exercising it several times. Start with the CDL - engage it, drive for a minute, disengage it. Rinse, repeat, wipe hands on pants. Then do the same for 4Lo-4Hi. The goal is really to have the actuator move back and forth a bunch of times so that it "cleans" the electrical contacts.

As @Supra88 notes, pulling the actuator and cleaning it thoroughly is (likely) the proper fix. However if you're not mechanically inclined then you have to find a shop willing to pull it apart correctly. Many dealers won't want to try to R&R and will simply try to have you buy a replacement actuator assembly and will then drop and open the transfer case in order to swap the entire thing.
I’d be willing to bet 99% of these problems are due to the air breather hose letting moisture in and then the connection between the contacts degrades due to oxidization.

I posted a YouTube video that walks you through my pain points. It’s a simple fix honestly. Just be methodical and thoughtful of what you’re doing.

The dealership is going to charge you at least $4000 for them to crack the transfer case and install a new actuator, for what? For a dirty contact!? I’d look for someone comfortable enough with electronics and mechanics to look at it if I was you - if you’re not able to DIY it.
 
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Messages
1,190
I’d be willing to bet 99% of these problems are due to the air breather hose letting moisture in and then the connection between the contacts degrades due to oxidization.

I posted a YouTube video that walks you through my pain points. It’s a simple fix honestly. Just be methodical and thoughtful of what you’re doing.

The dealership is going to charge you at least $4000 for them to crack the transfer case and install a new actuator, for what? For a dirty contact!? I’d look for someone comfortable enough with electronics and mechanics to look at it if I was you - if you’re not able to DIY it.
I was surprised just how oxidized the motor and the micro switch was. The metal was black and had intermittent continuity when activated. Contact cleaner cleaned it up like new and it works great now.

The hardest part is making sure to get the mechanism aligned correctly before reassembly, otherwise everything else is very accessible and easy to remove.
 
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I’d be willing to bet 99% of these problems are due to the air breather hose letting moisture in and then the connection between the contacts degrades due to oxidization.

I posted a YouTube video that walks you through my pain points. It’s a simple fix honestly. Just be methodical and thoughtful of what you’re doing.

The dealership is going to charge you at least $4000 for them to crack the transfer case and install a new actuator, for what? For a dirty contact!? I’d look for someone comfortable enough with electronics and mechanics to look at it if I was you - if you’re not able to DIY it.

Likewise, as seen in the picture, my microswitch was severely oxidized. I'm curious as to the moisture however. The breather was often an issue in older Tundras and Sequoias, but my breather was still intact and looked good. I'm in a relatively arid climate and still the oxidation. Still, multiple things to watch out for.
 
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wenatchee, WA
I was surprised just how oxidized the motor and the micro switch was. The metal was black and had intermittent continuity when activated. Contact cleaner cleaned it up like new and it works great now.

The hardest part is making sure to get the mechanism aligned correctly before reassembly, otherwise everything else is very accessible and easy to remove.
Did you re-grease the contacts with the same yellow stuff or leave it dry?
I concur with the hardest part being the need to make sure the mechanism is aligned/clocked correctly. This caused me hours over days of frustration. But if you’re careful and take the time to note the orientation and take pictures as you go, it’s and extremely easy fix. My motor was pretty rusty - but still operational - I bench tested it multiple times to make sure it wasn’t part of the problem, the root cause was the same black corrosion on the contacts, and intermittent continuity due to breather hose being loose/rotten on the end.
 
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Likewise, as seen in the picture, my microswitch was severely oxidized. I'm curious as to the moisture however. The breather was often an issue in older Tundras and Sequoias, but my breather was still intact and looked good. I'm in a relatively arid climate and still the oxidation. Still, multiple things to watch out for.
I’m wondering if it’s potentially where the breather hose connects - up the line maybe? I didn’t trace it back to verify the end point, but it might be worth knowing this. Perhaps moisture is getting in further up the line?

Or, maybe the ambient atmospheric moisture in the air and condensation - being as close to the exhaust pipe - I was wondering if the high temp swings of the actuator might cause a slight build up? It’s a long shot, but not implausible. Even in arid environments, if you’ve got temperature swings - you’ll see moisture in the form of condensation. 🤷🏼‍♂️ Just a thought.
 
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I’m wondering if it’s potentially where the breather hose connects - up the line maybe? I didn’t trace it back to verify the end point, but it might be worth knowing this. Perhaps moisture is getting in further up the line?

Or, maybe the ambient atmospheric moisture in the air and condensation - being as close to the exhaust pipe - I was wondering if the high temp swings of the actuator might cause a slight build up? It’s a long shot, but not implausible. Even in arid environments, if you’ve got temperature swings - you’ll see moisture in the form of condensation. 🤷🏼‍♂️ Just a thought.

Surely possible as the oxidation is coming from, and accelerated by, some form of heat and moisture. Start with some oxidation, increasing the resistance of the switch contact, only for it to further heat up and degrade.

It's interesting that the battery plays into this. Basic ohms law tells us that with lower voltages, either due to cold weather, weak batter, or both, that some draws will compensate with additional current. It's this current, mixed with minor oxidation/resistance, that's really bad for contacts and will destroy electronics in a hurry. Or replacing batteries will help it jump the oxidation/resistance that's been built up.
 
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Messages
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Did you re-grease the contacts with the same yellow stuff or leave it dry?
I concur with the hardest part being the need to make sure the mechanism is aligned/clocked correctly. This caused me hours over days of frustration. But if you’re careful and take the time to note the orientation and take pictures as you go, it’s and extremely easy fix. My motor was pretty rusty - but still operational - I bench tested it multiple times to make sure it wasn’t part of the problem, the root cause was the same black corrosion on the contacts, and intermittent continuity due to breather hose being loose/rotten on the end.
I purchased the correct grease for the application from an aircraft supplier, but I'd say there was enough extra grease in the unit from Mr. T where you could redistribute it where needed.
 
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Surely possible as the oxidation is coming from, and accelerated by, some form of heat and moisture. Start with some oxidation, increasing the resistance of the switch contact, only for it to further heat up and degrade.

It's interesting that the battery plays into this. Basic ohms law tells us that with lower voltages, either due to cold weather, weak batter, or both, that some draws will compensate with additional current. It's this current, mixed with minor oxidation/resistance, that's really bad for contacts and will destroy electronics in a hurry. Or replacing batteries will help it jump the oxidation/resistance that's been built up.
One of my troubleshooting steps was to unhook the battery leads and tap them together to drain any capacitors in the system to give it a hard reboot. A failing/bad battery as you mention can cause all sorts of gremlin’s to pop up and do weird things - as we’re seeing in some of these threads, especially when the issue arises in cold weather.
 

radman

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It's interesting that the battery plays into this. Basic ohms law tells us that with lower voltages, either due to cold weather, weak batter, or both, that some draws will compensate with additional current. It's this current, mixed with minor oxidation/resistance, that's really bad for contacts and will destroy electronics in a hurry. Or replacing batteries will help it jump the oxidation/resistance that's been built up.

I agree to all this; however, why would the CDL flash on starts when the button hasn’t even been pressed?
Is it possible Toyota is using this dash light for a secondary purpose? Apparently someone had gone into a dealer and they knew to use the CDL light as an indicator to weak battery.

My CDL is fully exercised and will immediately engage/disengage when i need it, but i still get a lot of flashing on cold mornings - especially when i leave my dash cams on
 
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I agree to all this; however, why would the CDL flash on starts when the button hasn’t even been pressed?
Is it possible Toyota is using this dash light for a secondary purpose? Apparently someone had gone into a dealer and they knew to use the CDL light as an indicator to weak battery.

My CDL is fully exercised and will immediately engage/disengage when i need it, but i still get a lot of flashing on cold mornings - especially when i leave my dash cams on

Most systems have some boot or BIT (built in test) routine on startup. The CDL system may not try to actuate on startup, but it very likely checks the state of all its inputs for integrity. In cold weather, either due to low voltage and/or electro-mechanical effects, the state of a switch or contact probably floats (non-conducting). When the system expects it to be closed high or low. Hence the CDL flash CEL.

A fresh battery with higher relative voltage, or warming up the car, is probably enough to overcome that contact/switch resistance issue. Then the problem goes away. Temporarily. As the root electro-mechanical contact issue is still there.
 

linuxgod

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I agree to all this; however, why would the CDL flash on starts when the button hasn’t even been pressed?
Is it possible Toyota is using this dash light for a secondary purpose? Apparently someone had gone into a dealer and they knew to use the CDL light as an indicator to weak battery.

My CDL is fully exercised and will immediately engage/disengage when i need it, but i still get a lot of flashing on cold mornings - especially when i leave my dash cams on
It's possible, but I'd say it's a self-test, I suspect. Or rather, it flashes because it's not seeing continuity on power-up, so it assumes the CDL is "missing". low battery would be an interesting answer but the frequency (or infrequency) makes me think that's not the case. I once drove 1000 miles from Chicago to Ouray. I hadn't seen the light flash in months. It was 45F out and the following morning at camp I started the vehicle and the light came on.
 

radman

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so that leads to a low battery right? they cutoff at what voltage?
I'll have to check what I have them on, but it has 3 thresholds at 11.3V, 11.8V or 12.1.

A fresh battery with higher relative voltage, or warming up the car, is probably enough to overcome that contact/switch resistance issue.

BIT makes sense.
For what it's worth, in my short testing to make the flashing turn off, my assumption is that the battery getting a quick top-off from the alternator is what's allowing the light to stop flashing after a restart - as opposed to the TC actually warming up to temp.
 

linuxgod

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I'm not gonna say it's not a low battery, but in the list of transfer case system problems/symptoms and suspected areas, low battery never comes up as a potential solution. Also all the troubleshooting docs basically say to confirm voltages are between 11-14V, which is a pretty broad range. If you're down around 11V your battery is in pretty bad shape. Also, as I noted in my case I've had the issue when the battery was surely fully charged.

1652730023119.png
 
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I'm not gonna say it's not a low battery, but in the list of transfer case system problems/symptoms and suspected areas, low battery never comes up as a potential solution. Also all the troubleshooting docs basically say to confirm voltages are between 11-14V, which is a pretty broad range. If you're down around 11V your battery is in pretty bad shape. Also, as I noted in my case I've had the issue when the battery was surely fully charged.

View attachment 3010360

Environmental/temperature is not identified either. Yet we know it's a variable, sort of.

A system that is new or in great working condition would have no problems with either. The problem comes when these systems degrade and become marginal, that variations on voltage and temperature, may just trip them up enough to work inconsistently. Which is what we're seeing.

Battery voltage effects become a symptom of the problem. So is temperature. Neither are necessarily a root cause which is what this thread is trying to help solve.
 

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