Code 1870 1996 Chevy Suburban 1500 PLEASE HELP !!

I can drive below 40 mph and nothing, once I hit the freeway engine light turns on and gears start slipping. I erase the code and it runs fine at first this would happen once in a while but lately its every time I get on the freeway. I cant keep driving and erasing the code, Every shop says I need to replace the transmission, any advice?

I can drive below 40 mph and nothing, once I hit the freeway engine light turns on and gears start slipping. I erase the code and it runs fine at first this would happen once in a while but lately its every time I get on the freeway. I cant keep driving and erasing the code, Every shop says I need to replace the transmission, any advice?

We can not advise without proper information.

Mileage and fluid condition and level and service history and if the transmission shop checked it out and tested it.

But here is some info on that code.

Diagnostic Information on DTC P0894 and P1870 #02-07-30-001A - (02/11/2004)
Diagnostic Information on DTC P0894 and P1870
2000-2004 Passenger Cars and Light Duty Trucks
2003-2004 HUMMER H2
with 4L60-E or 4L65-E Automatic Transmission
This bulletin is being revised to include additional model years and additional diagnostic information. Please discard Corporate Bulletin Number 02-07-30-001 (Section 07 -- Transmission/Transaxle).
Diagnostic trouble codes (DTC) P0894 and P1870, Transmission Component Slipping, may have different root causes. The following diagnostic tips are provided to assist in accurately repairing the condition.
Corporate Bulletin Number 01-07-30-023A, dated November 2001, is intended for 1996-1999 vehicles with more than 32,000 km (20,000 mi). This bulletin addresses wear in the valve body TCC isolator/regulator bore, which can cause DTC P1870. This wear condition is not the cause of DTC P0894 or P1870 on any 2000 model year vehicle built after January 15, 2000, or any 2001 or newer vehicles as the valve body used on these vehicles has been revised to prevent the wear condition.
Corporate Bulletin Number 99-07-30-005, dated March 1999, should be used to help with diagnosis of these DTC's. This bulletin will help to determine if the DTC is caused by the TCC system or by a slipping internal transmission component such as a clutch or band.
Slip speeds greater than about 250 rpm at steady state driving are caused by a slipping clutch or band.
Slip speeds below 250 rpm at steady state driving are usually caused by the TCC not applying but may also be caused by a slipping clutch or band.
A plugged or restricted TCC apply fluid orifice (238, located in the pump) may cause DTC P0894 or P1870, especially in low mileage vehicles with less than 8,000 km (5,000 mi).
A converter clutch valve (224, located in the pump), which does not have full travel of 13 mm (0.5 in) or is stuck in the off position may cause DTC P0894 or P1870. Inspect the valve for chips, debris, nicks or burrs. Also, inspect the springs (225 and 226) to make sure they are not limiting valve travel. A spring that is not fully wound may catch in the bore, limit valve travel and cause DTC P0894 or P1870.
A cracked or leaking TCC solenoid (part of harness 66) may cause DTC P0894 or P1870. Use solenoid test kit J 44246 to test the operation of this solenoid.
A cracked or leaking TCC PWM solenoid (396) may also cause DTC P0894 or P1870.
When attempting to diagnose a DTC P0894 or P1870, it is important to also refer to the appropriate Service Manual for further possible causes of this condition.

I can drive below 40 mph and nothing, once I hit the freeway engine light turns on and gears start slipping. I erase the code and it runs fine at first this would happen once in a while but lately its every time I get on the freeway. I cant keep driving and erasing the code, Every shop says I need to replace the transmission, any advice?


most transmissions of the vintage have worn control valves. loss of pressure results when the speed gets to the torque converter attempting to lock up @42MPH.

the transmission shop can replace the two valves and the cost is not that much.

don't use dexron III use the new GM approved dexron VI ..have the transmission fluid completely replaced ,when the valves are done.

most transmissions of the vintage have worn control valves. loss of pressure results when the speed gets to the torque converter attempting to lock up @42MPH.

the transmission shop can replace the two valves and the cost is not that much.

don't use dexron III use the new GM approved dexron VI ..have the transmission fluid completely replaced ,when the valves are done.

Replacing the TCC solenoids and pressure control solenoid is not hard. Messy, but not hard or expensive. IF that's the problem. The Dex VI is much better fluid, but I haven't read about its compatibility with the older 4L60E tranny. I must have missed how many miles you have on it, and how often the fluid has been changed.

Replacing the TCC solenoids and pressure control solenoid is not hard. Messy, but not hard or expensive. IF that's the problem. The Dex VI is much better fluid, but I haven't read about its compatibility with the older 4L60E tranny. I must have missed how many miles you have on it, and how often the fluid has been changed.


dexron VI is the replacement fluid and it states this on the container.