Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that something inside the car's transmission isn't working right. It's like when a bike chain slips off the gears, making it hard to pedal. In this case, the car might not change gears smoothly.
P1870 is triggered when the transmission control module (TCM) detects a problem with the transmission's ability to shift gears properly, often due to slipping or a fault in the 4x4 switch circuit.
The P1870 code indicates that the transmission control module has detected excessive slippage within the transmission components or a failure in the 4x4 switch circuit. This can occur due to worn-out clutches, bands, or other internal transmission parts, or due to an electrical fault in the transfer case switch circuit.
• Harsh or delayed shifting
• Transmission slipping
• Check Engine Light is on
• Poor fuel economy
• Vehicle stuck in one gear
• Worn or damaged transmission clutches or bands
• Faulty transmission fluid or low fluid level
• Malfunctioning 4x4 switch or circuit
• Internal transmission mechanical failure
• Faulty transmission control module (TCM)
Transmission: A system in a vehicle that transmits power from the engine to the wheels.
4x4 Switch: A switch that engages the four-wheel-drive system in a vehicle.
• Check the transmission fluid level and condition.
• Inspect the transmission for any leaks.
• Use a scan tool to read transmission data and check for any other related codes.
• Test the 4x4 switch and circuit for proper operation.
• Perform a transmission pressure test.
• Replace or repair worn transmission clutches or bands.
• Flush and replace the transmission fluid.
• Repair or replace the faulty 4x4 switch or circuit.
• Rebuild or replace the transmission if necessary.
• Reprogram or replace the transmission control module if faulty.
• OBD-II scan tool
• Transmission pressure gauge
• Multimeter
• Transmission jack
• Basic hand tools
$500 - $2500
Difficult
• Chevrolet Silverado
• GMC Sierra
• Dodge Ram
• Regularly check and maintain transmission fluid levels.
• Avoid aggressive driving that can cause excessive wear.
• Perform regular transmission maintenance.
Transmission Issue
• Avoid driving the vehicle if the transmission is slipping significantly.
• Seek professional diagnosis and repair to prevent further damage.
Transmission repairs may be covered under powertrain warranty if the vehicle is within the warranty period.
P1870 has been a common code for vehicles with high mileage or those that have not had regular transmission maintenance.
High – Driving with this code can lead to further transmission damage and unsafe driving conditions.
Ignoring transmission issues can lead to vehicle breakdowns and potential safety hazards.
• Vehicle should be at normal operating temperature.
• Test drive the vehicle to observe shifting behavior.
The transmission is located underneath the vehicle, between the engine and the driveshaft.
Q: Can I drive with a P1870 code?
A: It's not recommended to drive with a P1870 code, as it can cause further damage to the transmission.
Q: How can I prevent a P1870 code?
A: Regular transmission maintenance and avoiding aggressive driving can help prevent this code.
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