CEL & Check trans light are on

[VinceH]

I was driving home last night and all of the sudden both the CEL and check trans light came on. I have a 200 rodeo with 72,000mls. The truck runs great. I feel no slipping or any problems that would come from the trans. I was looking thru some of the post and found one that mentioned that it could be the alt or battery. Is this possible? I would like to know if anybody has had this issue and has found the cause and cure for this. Could the lights come on if the fluid dips bellow a certain level? Any help would be great.

[rodeo02]

Gotta read the codes Vince. I would not drive the truck much until you figure out whats going on. 4L30E's are not cheap to fix/replace. Try an autozone for a free code read, or pickup a $40 code reader from harbor freight tools.

Joel

[VinceH]

I just returned from having the code checked. It read p1870 Transmision component slipping. ANy thoughts?

[johnsm]

Originally Posted by VinceH

I just returned from having the code checked. It read p1870 Transmision component slipping. ANy thoughts?

Check the faqs. 1870 is a mystery code. Nobody knows a specific cure for it. I had it after I had a transmission leak. I had the tranny rebuilt to get rid of the code. The tranny guys said I could have gone another 20 000 kilometers before I would have had problems. Change your tranny filter and fluid and see if that fixes it. Check the battery and alternator outputs and check that all your ground contacts are clean and secure.


John

[VinceH]

Originally Posted by johnsm

Check the faqs. 1870 is a mystery code. Nobody knows a specific cure for it. I had it after I had a transmission leak. I had the tranny rebuilt to get rid of the code. The tranny guys said I could have gone another 20 000 kilometers before I would have had problems. Change your tranny filter and fluid and see if that fixes it. Check the battery and alternator outputs and check that all your ground contacts are clean and secure.


John

I can't imagine that there is a code that would indicate a problem and have it be a mystery code. Something is causeing this to fail and that is what I would like to find out. I don't really feal like bringing it to the dealership and say, here you go, fix it.(odds are that is what will happen).
I had the at fluid changed about 12k miles ago. I cant imagine that it would need to be changed again. I went 60k miles before that.

[surferfletch]

It's easy enough to check the fluid level/top off. I'd try that first.

[rodeo02]

I'd try another trans service and then maybe an ATF additive. The 4L30E's 'adjust' themselves for wear, so it's possible it's at the limit for adjustability. 60K is too long to go for an ATF change on these. Isuzu (like most manufacturers) is nuts to set the high mileage specs they do for ATF changes . I don't know if there is a way to force the check trans light to go out, but it still will be driveable for a long time. If it were mine, I'd do a fluid swap and filter change to get a look at the insides & use it as you normally would until the trans starts to act up. You have time to deside what you want to do, or shop around for a trans r/r. Typical 4L30E r/r will be pricey @ ~$2K.

G/luck
Joel

[johnsm]

Originally Posted by VinceH

I can't imagine that there is a code that would indicate a problem and have it be a mystery code.

No joke. I have talked to both dealers and independent tranny shops. They do not know what causes the 1870 code. Their only remedy for it is a rebuild. I talked to one independant tranny shop who sees this code come up in more than just the 4l30e transmission, they do more rebuilds on GM trannys than the Isuzus 4l30e. These were the guys who coined the phrase "Mystery code".

Here is proof that nobody knows what this code is about.
P1870 is transmission slipping. My Rodeo never had any signs of slipping and nobody who ever has reported having this code has ever experienced slipping or going into limp mode.

Go to a couple of shops and ask them about it. You will probably stumble on the one shop that does exclusive warranty work for the local gm dealers. See if they give you good advice.

John

[rodeo02]

Originally Posted by johnsm

No joke. I have talked to both dealers and independent tranny shops. They do not know what causes the 1870 code. Their only remedy for it is a rebuild..

John

Not unusal. Most are clueless on 'modern' stuff. People on these boards are more informed than they are.

Joel

[VinceH]

So I took it to a local shop and they came up with the problem as the torque convertor was slipping. basicaly when the car is cruising and in overdrive it is slipping slightly. He said that it was running about 300rmp faster than normal. So with that in mind I had him chande the fluid and filter, added an additive, cleaned out the debris.
We will see what happens next.(hopefully nothing)