The 99999999th P1870 thread
11-30-2007, 10:46 PM
#1
The 99999999th P1870 thread Okay, I searched the hell out of this and didn't find an answer to my question.
I have a freshly rebuilt tranny and a TCI 3500 stall that is a few months old. A few weeks ago the tranny burnt out the 3/4 packs, you know the drill. Rebuilt it, and within 10 miles I notice there is no lockup at all then the P1870 sets in the next time I drive. Now, I understand it is usually TCC slip related to the PWM, but with the code on my 1-2 shift is mushy as melted butter and the 3-4 is practically nonexistent. What it feels like is the 2-4 band is somehow not applying right. My first thought it the 2-4 apply servo, can anyone verify this? It would be a good excuse to upgrade to the corvette servo, but I don't know if it would set this code or not.
I have a freshly rebuilt tranny and a TCI 3500 stall that is a few months old. A few weeks ago the tranny burnt out the 3/4 packs, you know the drill. Rebuilt it, and within 10 miles I notice there is no lockup at all then the P1870 sets in the next time I drive. Now, I understand it is usually TCC slip related to the PWM, but with the code on my 1-2 shift is mushy as melted butter and the 3-4 is practically nonexistent. What it feels like is the 2-4 band is somehow not applying right. My first thought it the 2-4 apply servo, can anyone verify this? It would be a good excuse to upgrade to the corvette servo, but I don't know if it would set this code or not.
11-30-2007, 11:00 PM
#2
The code means componet slipping but its ony set if lockup is turned on, Ussually its the converter clucth/pwm/ or something to do with it, The tcc is comanded on and the converter clutch does not engage and the PCM sees to much slip. Iwould only think that a clutch set could set it slipping if it was in 3rd or 4th gears. Sounds like you have a slipping band and or low line presure which could also set the code , If the line presure is good the firstthing I would do is inspect the servos. for leakage but if thats not the case you may have some sort of internal leakage. affect the shifts and the converter clutch operation. If this is a camaro you probably have the corvette servo allready
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11-30-2007, 11:56 PM
#4
If it locks in 3rd then the band slipping is likley the issue could be the servos I would look there first then. It and unussual situation but slipping band in OD could indeed set that code , Its set when the slip is more than 40 rpm in 4th gear with the converter locked. Thats why when may people say that they have 1870 that thats there converter is comanded to lock but isnt ,or visa versa if that code does not show then the converter is not being commanded to lock by the PCM
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Last edited by performabuilt; 12-01-2007 at 11:08 AM.
12-01-2007, 11:27 AM
#6
Glad I could help , To reveiw-
PO1870 is set when the converter is comanded to lock in 3rd or 4th gears and this does not happen causing the RPM differential to show 40+ rpm of slip when the converter is supposed to be locked. This can also occur in the same situation if the 3-4 clutch or the 2-4 band is slipping excessivley, If either of these conditions exsist and there is no PO1870 then one of two things has happened , The converter was not comanded locked by the PCM or the test for the CODE has been removed from the system through tuning such as might be done with a non lockup converter.Alternatley if the converter is comanded to lock and this code comes up either the converter failed to engage for some trans/converter related issue or the trans is slipping in 3rd or 4th gear and the converter did lock.
So to sum it up if you dont have lockup and the car is at operating temperature and you do not have lockup , But also do not have this code then your failure to have lockup is a tuning issue. Below is the copied explanation from a manual for the code.
"The Powertrain Control Module (PCM) monitors the difference between engine speed and transmission output speed. In D3 drive range with the Torque Converter Clutch (TCC) engaged. the engine speed should closely match the transmission output speed. In D4 drive range, with the TCC engaged, the TCC slip speed should be -20 to +40 RPM. The table indicates solenoid states and transmission components that apply, during 4th gear, with the TCC commanded ON.
When the PCM detects excessive TCC slip when the TCC should be engaged, then DTC P1870 sets. DTC P1870 is a type B DTC "
So basically 1870 should set if the cars in third or 4th gears and the converter as comanded to lock and either it dosent or theres another "componet slipping" causing and excessive rpm differential or slip between engine rpm and expected output speed.
Another thing that also could cause this would be rear differential changes that have not been calbrated. This is why when I hear someone say there converter is not locking up. I first ask them if this code is there and if not direct them to look at tuning or running issues that might prevent lockup from being comanded.
Also note if PWM is functional the amount of slip allowed can change. None or out units have functional PWM all have been modified for simple on off operation, Reguarless of the PWM percentage comanded.
PO1870 is set when the converter is comanded to lock in 3rd or 4th gears and this does not happen causing the RPM differential to show 40+ rpm of slip when the converter is supposed to be locked. This can also occur in the same situation if the 3-4 clutch or the 2-4 band is slipping excessivley, If either of these conditions exsist and there is no PO1870 then one of two things has happened , The converter was not comanded locked by the PCM or the test for the CODE has been removed from the system through tuning such as might be done with a non lockup converter.Alternatley if the converter is comanded to lock and this code comes up either the converter failed to engage for some trans/converter related issue or the trans is slipping in 3rd or 4th gear and the converter did lock.
So to sum it up if you dont have lockup and the car is at operating temperature and you do not have lockup , But also do not have this code then your failure to have lockup is a tuning issue. Below is the copied explanation from a manual for the code.
"The Powertrain Control Module (PCM) monitors the difference between engine speed and transmission output speed. In D3 drive range with the Torque Converter Clutch (TCC) engaged. the engine speed should closely match the transmission output speed. In D4 drive range, with the TCC engaged, the TCC slip speed should be -20 to +40 RPM. The table indicates solenoid states and transmission components that apply, during 4th gear, with the TCC commanded ON.
When the PCM detects excessive TCC slip when the TCC should be engaged, then DTC P1870 sets. DTC P1870 is a type B DTC "
So basically 1870 should set if the cars in third or 4th gears and the converter as comanded to lock and either it dosent or theres another "componet slipping" causing and excessive rpm differential or slip between engine rpm and expected output speed.
Another thing that also could cause this would be rear differential changes that have not been calbrated. This is why when I hear someone say there converter is not locking up. I first ask them if this code is there and if not direct them to look at tuning or running issues that might prevent lockup from being comanded.
Also note if PWM is functional the amount of slip allowed can change. None or out units have functional PWM all have been modified for simple on off operation, Reguarless of the PWM percentage comanded.
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