A/T Oil Light 4WD- Toyota

[rubicon327]

Originally Posted by Brian B-P

If it's the 5-speed, this is presumably the Aisin-Warner A750F... anybody familiar with the internals of that one?

Brian: In 2004 the V6 was mated with a 4 speed automatic. Is it possibly the A340F?

[Dave Walter]

My experience towing a 19' with an FJ cruiser equipped with a scangage to monitor transmission temps is that under most towing conditions driving in 4th gear rather than D (5th) results in substantially lower transmission fluid temperatures. Unless I am on flat ground with no head winds it is a no brainer for me to tow in 4th gear.

[John in Santa Cruz]

Originally Posted by rubicon327

Brian: In 2004 the V6 was mated with a 4 speed automatic. Is it possibly the A340F?

probably that or the A340E, essentially the same thing. This is the same transmission that Volvo used on their inline-6 3L powered 960 luxury sedan/wagons of the mid 90s (Volvo called it an AW30-43). Again the Volvos were very specific about no towing in 4th/Overdrive as that was a 'side gear' tucked into the front of the transmission, and quite fragile, meant only for cruising. We had a 960 wagon, and used to tow a utility trailer full of camping/festival gear, that car was a trooper, was very sad when it got tail ended by a moron and totalled.

[Brian B-P]

Originally Posted by rubicon327

Brian: In 2004 the V6 was mated with a 4 speed automatic. Is it possibly the A340F?

Yes, that makes sense. The original post didn't say which transmission, both were offered in that generation of 4Runner, and the manual doesn't say which transmission goes with which engine.

Originally Posted by John in Santa Cruz

probably that or the A340E, essentially the same thing.

The final letter general indicates 2WD versus 4WD versions, so it does make sense that they would be internally the same and that the 4WD 4Runner would have the A340F... but it could also have the A340H (listed in Wikipedia as used for the 4Runner "w/ V6 and ECT (electronic controlled transmission)").

Originally Posted by John in Santa Cruz

This is the same transmission that Volvo used on their inline-6 3L powered 960 luxury sedan/wagons of the mid 90s (Volvo called it an AW30-43). Again the Volvos were very specific about no towing in 4th/Overdrive as that was a 'side gear' tucked into the front of the transmission, and quite fragile, meant only for cruising

Toyota doesn't seem to have the same concern. Perhaps because Toyota only used the A43 with four-cylinder engines...

A gear on the 'side' of a longitudinal automatic doesn't make much sense. An exploded view of the A340 shows the overdrive planetary gearset as the first (closest to input end) of three in the transmission. There's nothing "tacked on" about it - it's just another planetary set with clutch packs to engage one of two paths through it.

As with most automatics of this vintage, one gear is direct drive all the way through the transmission, with no gears transmitting power (just clutches); that's 3rd gear in this case, which is why it may be preferred. For fluid heating, that won't be important - avoiding unlocking the torque converter is the important part. Yes, that might mean not using the highest gear ratio.

[rubicon327]

Originally Posted by Brian B-P

Yes, that makes sense. The original post didn't say which transmission, both were offered in that generation of 4Runner, and the manual doesn't say which transmission goes with which engine.

I only know the 4 speed was mated with the V6 in 2004 because I was shopping for that vintage 4Runner a few years ago. Only the V8 in 2004 had the 5 speed. My 2005 does have the 5 speed with the V6.

No one has addressed that the OP was in 4 wheel drive. He never indicated if the center differential was locked or not. These vehicles have essentially an option for 2WD, 4WD with open center differential, and a true 4WD with center differential locked. I'm not sure how much it matters, but that is why I'm asking. Would being in 4 wheel drive during a climb with increased stress on the transmission cause the A/T oil temp light to come on? He indicates it is not coming on in 2WD. Below is an excerpt from top4Runners.com regarding the drivetrain system on a 2004 4Runner:

"The V6 is paired with an electronically controlled four-speed automatic overdrive transmission (4ECT-i). All 4WD 4Runners are equipped with a two-speed transfer case with increased torque capacity. A Multi-Mode shift-on-the-fly 4WD system with a Torsen sensing type limited-slip center differential is standard on all 4Runners with a V6 engine and 4WD. 4Runner was one of the world’s first to use the Torsen® sensing type limited-slip center differential in a mid-size SUV transfer case. The Multi-Mode 4WD feature is an open center differential with locking capability that provides a full-time 4WD system with the ability to select 2WD mode. The 4WD mode may be used in normal driving conditions on all types of roads from dry, hard surface roads, such as pavement, to wet or snow-covered roads. Driving with the Multi-Mode’s 4WD system engaged provides the driver with a more sure-footed feel because power is applied to all four wheels, improving traction.

The torque-sensing feature allows the torque split mid-point to be more biased toward the rear, sending more torque to the rear wheels, providing better stability control whether the driver is accelerating at high or low speeds. The static rear-drive bias favors stable tracking on- or off-road, decelerating or accelerating. The Torsen type sensing differential provides three dynamic torque split ratios, depending on the available traction on the vehicle at the time. A static torque split favors the rear with a 40/60 percent front-to-rear split. When the front wheels slip, up to 71 percent of the split ratio goes to the rear wheels. When the rear wheels slip, up to 53 percent of the split is applied to the front wheels."

[thiggins]

As others have said, you should probably get the fluid changed out. If the lights indicated overheating, the transmission fluid has been cooked.

If you decide to add a cooler, be very careful about how it's installed and get a good one, hopefully with threaded fittings, not the squishy compression type rubber hoses with worm type clamps, but real braided lines with good quality threaded fittings. ( How do I know this? ...please don't ask...$$$$$....)

There may also be an aftermarket transmission pan available for your truck, that will give you additional cooling and fluid capacity. They usually also include a drain plug, which makes maintaining nice fresh fluid a snap.

I believe in making what you have work, you own it by golly.

[davedru]

Thanks for the replies everyone. First of all, it is indeed the 4 speed, so I can't select "4" only 3, 2, or L. I did have the the system in locked 4wd drive mode when it was overheating.

The rig did have the tow package, so I'm assuming it does have a transmission cooler?

I will get the transmission fluid changed asap, and ordered an OBD2 reader so that I can watch the trans temp.

I am still a little confused about whether this system is full time 4wd or not, and that the dial that indicated 2wd or 4wd is the locking system?

[Rossue]

If you take your VIN into a dealer they can give you a printout of everything your vehicle has. Then they can tell you for certain about your 4 WD question.

[John in Santa Cruz]

Originally Posted by davedru

Thanks for the replies everyone. First of all, it is indeed the 4 speed, so I can't select "4" only 3, 2, or L. I did have the the system in locked 4wd drive mode when it was overheating.

The rig did have the tow package, so I'm assuming it does have a transmission cooler?

I will get the transmission fluid changed asap, and ordered an OBD2 reader so that I can watch the trans temp.

I am still a little confused about whether this system is full time 4wd or not, and that the dial that indicated 2wd or 4wd is the locking system?

a Tacoma with the 2H/4H/4L switch is traditional 4x4, and in 2H, you are only driving the rear wheels. you should NEVER use 4H on pavement, unless its very muddy/slippery or snow/ice covered.

[AKCamper]

Originally Posted by davedru

Thanks for the replies everyone. First of all, it is indeed the 4 speed, so I can't select "4" only 3, 2, or L. I did have the the system in locked 4wd drive mode when it was overheating.

The rig did have the tow package, so I'm assuming it does have a transmission cooler?

I will get the transmission fluid changed asap, and ordered an OBD2 reader so that I can watch the trans temp.

I am still a little confused about whether this system is full time 4wd or not, and that the dial that indicated 2wd or 4wd is the locking system?

Make sure the OBD2 reader will read transmission temperature. Looks like the ScanGauge II or the UltaraGauge MX works on most vehicles (recommend checking before purchase).

[rubicon327]

Originally Posted by davedru

Thanks for the replies everyone. First of all, it is indeed the 4 speed, so I can't select "4" only 3, 2, or L.

Yes, the manual for the 2004 with 4 speed indicates:
"Do not continue hill climbing or hard towing for a long time in the “2” or “L” position. This may cause severe automatic transmission damage from overheating. To prevent such damage, “D” or “3” position should be used in hill climbing or hard towing."

Originally Posted by davedru

The rig did have the tow package, so I'm assuming it does have a transmission cooler?

I don't think 4Runners have what is typically thought of as a "tow package". They were all factory equipped with hitch, 7 pin connection and 5,000 lb towing / 500 lb tongue weight out of the box with the weight carrying hitch. The transmission should have lines that run to a stock cooler that is integral with the radiator. Some guys have added external coolers as they believe they work better.

Originally Posted by davedru

I did have the the system in locked 4wd drive mode when it was overheating.

Originally Posted by davedru

I am still a little confused about whether this system is full time 4wd or not, and that the dial that indicated 2wd or 4wd is the locking system?

Dave: Read your manual or pages 156-167 at the link below. The 4Runner has a very sophisticated multi-mode drivetrain. It has capabilities of 2WD, 4WD HI (unlocked), 4WD HI (center differential locked - using push button on dash), 4WD LO (unlocked) and 4WD LO (center differential locked). Omit 2WD if you happen to have a full-time 4WD model (by your statement above this appears to not be the case) (On edit: full-time 4WD only available with the V8).

The large dial on the dash only puts you in 4WD HI or LO unlocked mode (indicated by only the green indicator light on the dash with front wheels skewed slightly sideways). To be in the locked 4WD mode you need to hit the button to the left of the steering wheel. See picture attached. When you are in locked 4WD mode an additional yellow indicator comes on the dash with an "X" between the axles and the "VSC OFF" lights up.

https://cdn.dealereprocess.net/cdn/s...04-4runner.pdf

By the way, I believe you have to opt for the top Limited trim on the newest 4Runners to get this same functionality. I have a 2005 and really love the drive train. It is the best of both worlds between my old Jeeps and a Subaru AWD system.

[rubicon327]

Originally Posted by John in Santa Cruz

a Tacoma with the 2H/4H/4L switch is traditional 4x4, and in 2H, you are only driving the rear wheels. you should NEVER use 4H on pavement, unless its very muddy/slippery or snow/ice covered.

Not true for the 4th gen (2003-2009) 4Runners though. As per my previous post:
"The Multi-Mode 4WD feature is an open center differential with locking capability that provides a full-time 4WD system with the ability to select 2WD mode. The 4WD mode may be used in normal driving conditions on all types of roads from dry, hard surface roads, such as pavement, to wet or snow-covered roads. Driving with the Multi-Mode’s 4WD system engaged provides the driver with a more sure-footed feel because power is applied to all four wheels, improving traction."

Now if you lock the center differential on the 4Runner then the end of your statement above applies. Should only use 4 HI locked mode in slippery road conditions.

[rubicon327]

...and with all that I posted above there is nothing that specifically states in the manual to avoid 4WD when towing. My take based on the system design is that 4 HI (unlocked) is preferable and 4 HI (locked) be used only if the conditions are going to allow the wheels to slip. Otherwise you can get binding when turning as the wheels cannot turn at different rates.

[John in Santa Cruz]

it depends on exactly which system you have. the /only/ time you use the differential lock on my Tacoma is when you're in deep dirt. later Tacomas have a*trac or v*trac, and are more dynamic/auto.

[rubicon327]

Originally Posted by John in Santa Cruz

it depends on exactly which system you have.

I completely agree, which is why everything I stated in this thread was intended to directly apply to the OP's 2004 4Runner V6.

[davedru]

Again- thanks everyone. I got the transmission fluid changed, added a tranny temp monitor, and will probably add a transmission cooler as well. I bought this thing for the mountains, so I guess I will have to take some extra precaution to keep from heating up again.

Also appreciate the information on my specific 4wd system, that is helpful to understand. I'm in the snow not in the dirt, so doesn't sound like I sound lock my diff for any of the typical conditions that I run into.

[rubicon327]

Originally Posted by davedru

Also appreciate the information on my specific 4wd system, that is helpful to understand. I'm in the snow not in the dirt, so doesn't sound like I sound lock my diff for any of the typical conditions that I run into.

I'm glad the information helped. You may certainly need H4 locked on steep, snow covered roads when you are going skiing. You are chasing powder, right?! The manual simply states: " “H4” (high speed position, four-wheel drive, center differential locked):... Use this for greater traction when you experience a loss of power, such as wheel slipping, in the center differential unlock mode."

So my approach would simply be H2 or H4 unlocked in normal conditions and then engage the center diff for H4 locked if conditions deteriorate. Then if things get really bad you still have L4 unlocked and locked...at which point you might want to turn around! My only concern arose in post 27 when you said you were in locked 4WD mode, but never mentioned the actual road conditions. If this was on dry pavement it would be adding unnecessary stress to the whole drive train and possibly contributing to the transmission overheating issue.

[Bill and Earline]

Dave,
I didn't see this thread until today, so glad all the other posts have you headed in the right direction. For the first couple of years and over 20,000 miles, we towed our 21' with our 2003 4Runner Sport 4.0, which is still doing fine in its retirement, and never will be for sale.

I changed the trans fluid each 50,000 miles (twice now) and used synthetic this last time. I also have the ScanGauge II, as others have mentioned, and I added a passive fluid cooler in front of the radiator.

Now that you have a gauge to monitor the temps, the next question is, what temp is safe. I contacted Purolator's tech rep, and was told that the synthetic fluid could handle much higher temps, but the transmission components might not, an that he would back off or pull over if temps exceeded 245F. By downshifting I was able to keep the temps below 225. There are charts the show how certain high temps decrease the life of the fluid dramatically, and Toyota should have a lower temp before the light comes on. Nevertheless our 4Runner is still one of our favorite cars after nearly 15 years and about 105,000 miles.

[davedru]

Thanks Bill - appreciate the comments from someone with a similar 4runner.

When the tranny was overheating, I did have the system in 4wd, but did not have it locked. I have never run into any problems with traction in this mode even in deep snow. That is why I was surprised to be overheating- I was at low RPM's in both cases. The temp monitor should help me avoid this situation in the future, and I will take your lead with with the fluid cooler as well.

[Bill and Earline]

I'd try it for a while without the cooler. As long as you can see the temperature of the transmission, you can drive accordingly. A downshift gives an almost immediate drop in temperature. The engine can take rev's into the 3500 to 4000 range for a while if needed to help with lowering temps. With the 4-speed, I used third freely, second, if needed, and for extra steep, first gear once. Then there was that time going up the steep part in Big Bend N.P. when I kept stopping to "take pictures" which was nothing more than letting temps drop a bit.