Service Engine soon Light (Code P1870)

Johnnyred2K4 · November 1, 2004

I have a 1998 GMC serria 1500 2wd. I recently bought 18in wheels w/ 285/60/18 tires. I also put a flowmaster duel in duel out muffer on. Other than that it's all stock. My question is ...Has anyone ever had problems with the "service engine soon"(Code P1870) light on because of the changes listed above. Sometimes the truck wil shift hard into 2nd and 3rd. Sometime it doesn't even do it at all. Here lately it's been doing it after a good while driving (20-35 min). After the truck is turn off. It doesn't do it again until driving a while. Any thoughts?

Also would a hypertech programmer fix it.? Just wondering if anyone has had this problem and if so what was the fix?

Peter_C · November 1, 2004

How many miles? Sounds like the TCC is going out. Rebuild time? The bigger tires probably helped cause the problem by applying more torque to the transmission. Basically the code is probably set in your case when the transmission slips for more than 8 seconds.

When the TCC engages is it pretty firm or a slug?

02 Silverado Z71 · November 1, 2004

P1870 is a transmission slip code. For years, the thransmission valvebody was the culprit; it would actually warp and then the internal valves would not function like they should.

Suggest looking into a valvebody, and maybe tearing the trans down to make sure nothing else got burned up BECAUSE of the valvebody problem. If you are not confident, check into your local trans shop.

Johnnyred2K4 · November 1, 2004

P1870 is a transmission slip code. For years, the thransmission valvebody was the culprit; it would actually warp and then the internal valves would not function like they should.
Suggest looking into a valvebody, and maybe tearing the trans down to make sure nothing else got burned up BECAUSE of the valvebody problem. If you are not confident, check into your local trans shop.

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Johnnyred2K4 · November 1, 2004

P1870 is a transmission slip code. For years, the thransmission valvebody was the culprit; it would actually warp and then the internal valves would not function like they should.
Suggest looking into a valvebody, and maybe tearing the trans down to make sure nothing else got burned up BECAUSE of the valvebody problem. If you are not confident, check into your local trans shop.

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The truck has 89K miles. What is TCC? I hope this isn't an expenisve fix or is it?

Peter_C · November 1, 2004

I should have said the Lock Up Converter. It locks the converter up for no slip when on the throttle while cruising down the road in OD. They use the RPM of the engine and the RPM of the transmission to determine if it is slipping or not. Most likely it is gonna take some parts to repair and at 89K it might be worth it to have the trans rebuilt especially if you are having other shift problems.

Johnnyred2K4 · November 1, 2004

Peter,

Thanks for all the input. Not really looking forward to rebuilting the tranny.

Thanks again

mcreyaufmiller · November 5, 2004

There is a shift kit avaiable aftermarket to fix this problem. I had the same problem for 2 years and all tranny shops told me 1 day and $350 to install the kit. I bought the partrs off the net and did it myself in the truck, no more problems. To install the kit, you drop the tranny pan, remove the valve body and follow the directions. There is one piston that needs to be replaced that is in the pump housing but the whole job is pretty easy. The kit does not include the gasgets, but they are cheap. email me if you want more information.

Mike

helomechs · September 30, 2008

There is a shift kit avaiable aftermarket to fix this problem. I had the same problem for 2 years and all tranny shops told me 1 day and $350 to install the kit. I bought the partrs off the net and did it myself in the truck, no more problems. To install the kit, you drop the tranny pan, remove the valve body and follow the directions. There is one piston that needs to be replaced that is in the pump housing but the whole job is pretty easy. The kit does not include the gasgets, but they are cheap. email me if you want more information.

Mike

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