Code PO1870

[chief153]

My 1997 LeSabre (150K miles) is giving me a PO1870 code after overdrive engages, this is the only time the check engine light comes on. I can turn the light off and it comes back on again maybe 900-1200 miles later. The shifts in the first three gears are normal. Filter and fluid have been changed recently and I found nothing unusual in the pan. I used Dextron III for the refill, maybe I should have used the new Dextron VI instead. Different listings show my trans to be a 4T65E, however it has a modulator valve which would point to a 4T60E.
HotZ28 has posted in different threads the best thing to do is take it to a trans. shop and have it tested, which I intend to do after the holiday, however I have read that there is a control valve in the vb that controls the tcc and it can be removed and replaced with an updated unit after reaming the hole it went into. I was curious to see if anyone here had made that repair.
With the milage on my auto it may be better to just replace the trans, the engine still uses no oil and gets 30mpg.

[gob 455]

P01870 transmission component slipping. I've seen this problem come through my shop a few times. The lockup torque converter is slipping. The compueter reads engine RPM and trans RPM, the numbers should be almost, if not exactily the same. If it sees plippage more than 250 RPM (i think), it will set this code.I havent heard of an updated part to fix this but, people are always thinking. The last trans I had come in with this problem, I did a fluid and filter service and added Lub-Guard in the red bottle (it's the only trans additive I use) and they haven't been back sence. But it's my experince that once the converter starts slipping, it's only a mater of time before it fails. This won't necessarily cause the trans to fail complitily, but you will have too remove the trans to replace the converter. You probibily should rebuild the trans if this happens.

[chief153]

I have heard about lube-guard, in the past I have always used seafoam. Seems lube-guard adds friction modifyers or something like that. I figure a reman trans is in the future at any rate.

[maxwedge]

The most common cause of this code is a loss of pressure to the lock up as a result of the TCC valve in the valve body wearing the bore it rides in, the resultant loss of tcc engagement pressure causes the pcm to boost pressure to compensate. I'd look into this first. This can be confirmed with a full scan of the trans functions, they make a repair kit to correct the condition that does not require an overhaul.

[BNaylor]

The Lubegard is a friction modifier additive which may or may not work on this particular issue. The Seafoam tranny treatment is really a cleaning/flushing agent. After use of Seafoam the ATF should be drained out and replenished. Then add Lubegard.

I recall for 4T60E or 65E autotransaxles companies like Sonnax or Transgo make a valve body repair kit to correct the TCC apply problem causing the P1870 DTC.

[chief153]

BNaylor, thanks for the reply. I have printed some photos and literature from the Sonnax website to show to my trans repairman tomorrow, hopefully he has performed this job before and is aware of the repair procedures.

[Jrs3800]

Yes the TCC Valve bore can wear causing the Trans to drop out of TCC lock...

Its possible for the TC to be slipping but chances are this isn't the case... The cause could be the Valve bore... As stated there are a couple of kits that will correct for the problem...

Some of the time the 4th gear slip could be the 4th clutches and or in rare cases the 4th input shaft..

In the 2 4T60-E's I pulled apart both of them had pretty well worn 4th input shaft teeth... And on one of them the 4th clutches were burnt..

So there are few things that will cause the slip codes.. Also wondering if you have any idea hot hot the transmission is getting? I have seen 4T60-E's easily get to 230-240F on a warm day...

[chief153]

I have an infrared heat gun, and on an average summer day the temps are around 200 degrees, I took these readings from the oil line going into the radiator, probably not a good location, but it gave me a base idea of what was going on. I installed a trans oil cooler on another LeSabre I had and the temp drop from inlet to outlet was 30 degrees. If I can get the problem on this car straightened out I intend to install a cooler on it too.
I put around 150 miles on the car today and the light did not come on. I`m going to drain the transaxle tomorrow and add a bottle of lubegard with the fluid change, if this makes no change then it`s to the transmission shop. Thanks to everyone for the valuable info.

[chief153]

I drained my fluid today and replaced it with Dextron VI and a bottle of lubegard. I noticed my shifts were more crisp and firm, however it is way too soon to see if this change has fixed my TCC problem, I`m not a believer in miracle cures, but hey, who knows it might work. I went to a trans. shop today to have some tests run, when I told the owner what code I had he wanted to know if my truck was a two or four wheel drive, duh, time to find another shop. He said automobiles didn`t give an 1870 code only pickups, wonder how he has stayed in business this long !!!!!
BTW, if anyone decides to go with Dextron VI be prepared to give at least $7 a quart, I was shocked at the price until I noticed it was fully synthetic.

[BNaylor]

Actually Dexron VI is supposed to be a synthetic blend ATF. I've used it very successfully on '98 and up GM cars with the 4T65E and HD version autotransaxles. I no longer use the old Dexron III.

I used the Walmart Supertech brand Dexron VI for $3.00 per qt. It is just my imagination or does that stuff smell like ginseng to you? Definitely doesn't have the nasty smell of Dex III.

At least we have documentation of an owner with a 4T60E using Dexron VI. Good luck and let us know how it turns out.

[chief153]

Originally Posted by BNaylor

Actually Dexron VI is supposed to be a synthetic blend ATF. I've used it very successfully on '98 and up GM cars with the 4T65E and HD version autotransaxles. I no longer use the old Dexron III.

I used the Walmart Supertech brand Dexron VI for $3.00 per qt. It is just my imagination or does that stuff smell like ginseng to you? Definitely doesn't have the nasty smell of Dex III.

At least we have documentation of an owner with a 4T60E using Dexron VI. Good luck and let us know how it turns out.

BNaylor I wish I had checked at Wal-Mart first before buying my fluid, I got Castrol brand at Advance Auto, sure hope I haven`t opened a bigger can or worms by putting this type fluid in a 4T60E, oh well time will tell!! I`ll post again later after I put some more miles on the car and let everyone know whether it helped or hurt. BTW the Dextron VI does smell different from Dex III. Please excuse my mistake on stating that Dextron VI was fully synthetic, I sure don`t want to mislead anyone on here.

[BNaylor]

Hard to say but many will be very curious about using it in a 4T60E. We have plenty of data it works in a 4T65E before the 2006 model year when GM started using it at the assembly line.

Yeah, I had to go to 3 out of the 10 Walmarts we have in our area to round up 8 qts on the last tranny I did. One associate told me they don't carry it. But obviously he had his head up his you know what. For the non believers here is a pic of the stuff.

[Jrs3800]

Yes that guy was an idiot... I work for wally... We have a lot of um, ahh... Really intelligent people...

Wal Mart does sell the Dex 4 but some times its hard to get, and if you can get it you may not get all you need, much was the case with you Bob..

I believe that the products you buy under the SuperTech Brand are actually Penzoil owned by Shell iirc... I have used their Trans fluid for many years, and know people who have used their oil and synthetic oil for 200k... so its decent stuff either was we look at it..

[Rasp]

Actually doesn't VI mean Dexron 6??? I'm not great at my Roman numerals but I'm sure VI means 6.

And if thats true what happened to 4 and 5.

[maxwedge]

They can be used on older cars from 2006 down I believe, yes VI is 6, synthetic. VI can be retrofiited to all the previous years.