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September 15, 2003
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超过1870：GM转换器代码P0741，P0742和1887

格雷格·纳米德

通用汽车臭名昭着的麻烦代码P1870自1995年以来一直存在，非常熟悉传播shops. P1870 is a “manufacturer specific” OBD-II trouble code used by GM. The official description is “transmission component slipping,” indicating problems with TCC performance on4L60-E.那4L80-E.那4L30-E.and4T60-E传输。

通用型号4T40-E.那4T65-E.那4T80-E.和土星传输，不要使用p1870代码。这些模型使用“通用OBD-II传输系统”代码P0741“TCC陷入”表示TCC性能问题。一些传输使用P0741和P1870都使用P0741和P1870。4L80-E传输使用P0741进行第三齿轮TCC滑动，并为第4齿轮TCC滑动的P1870。一些晚期的4L60-E传输可以设置P1870或P0741，具体取决于计算机的编程方式。

GM uses code “P0742 TCC Stuck On” when the computer detects the TCC has not released. P0742 is most often encountered on 4T40-E and 4T65-E transmissions units that have a TCC Release Pressure Switch. This switch is located in the TFP (Transmission Fluid Pressure switch assembly) mounted to the valve body. The TCC release pressure switch is used to verify TCC applies and releases when commanded by the PCM by indicating if TCC release pressure is present (the oil pressure that keeps the TCC piston in the released position).

当TCC释放电路中大约有20psi的油压时，TCC释放压力开关通常关闭并打开（参见图1). The switch is closed when the engine is off or when the TCC is locked up. The switch is open whenever the engine is running and the TCC is NOT engaged. Units with a TCC release pressure switch also have a diagnostic code P1887 for pressure switch performance.

在4T40-E或4T65-E传输上诊断代码P0742时，请查看扫描工具数据以查看是否存在释放压力“是”或“否”。监控交换机和计算机之间的信号线上的电压可能会有所帮助（参见图2用于连接线位置）。将扫描数据或电路电压与图表进行比较图3.and verify correct operation. On units with a TCC release pressure switch, codes P0742 & P1887 are just as likely to be caused by a defective TFP, electrical or connecter problems as by internal transmission problems.


In late model vehicles, it is becoming mandatory to check for computer program updates when diagnosing codes.图4.是GM地址与重新编程的TCC代码的一个例子。要检查更新的程序，所以所有您需要的是您正在处理的车辆的车辆识别号码。GM网站是免费的，不需要密码。


P0741 TCC陷入困境
如果PCM在命令TCC时检测到高转换器滑动，则将设置DTC P0741。在相同的点火周期中必须存在以下两个条件。

此代码将为所有相同的原因设置为P1870将设置：

  • TCC占空比大于50％
  • The TCC slip speed is greater than 180 RPM for 7 seconds
  • 在4L80-E变速器上的第3齿轮中的TCC滑动
Known causes for P0741:
  • 在阀体中穿过TCC阀门孔
  • 泵轴承密封损坏或磨损
  • 有缺陷的TCC PWM或TCC应用螺线管
  • 限制分离板电磁馈电孔口
  • Defective converter
  • Computer reprogram
  • Channel plate sleeve & turbine shaft sealing ring damage


P0742 TCC卡于4T40-E＆4T65-E
当计算机释放TCC时，TCC释放开关表示无释放压力（开关关闭或接地）然后P0742套。

这段代码可以由电机或液压problems.

P0742的已知原因：

  • 缺陷TFP（流体压力开关）
  • 有缺陷的TCC PWM电磁阀
  • TCC释放开关信号电路中间歇性短路
  • 线压力的快速波动。如果线压降非常低，转换器电荷油将受到限制，并且释放压力开关将关闭
P0742 TCC STUCK ON ALL GM UNITS
When the PCM detects low slip speed with TCC commanded off.

P0742的已知原因：

  • 坚持TCC涂抹阀门
  • 有缺陷的TCC PWM或TCC应用螺线管


P1887 TCC发布开关故障

When TCC is commanded on, and slip speed indicates that the converter clutch IS applied and the TCC release switch indicates the converter clutch is NOT applied, then the P1887 will set.

这段代码可以由电机或液压problems. It is possible to have a normally working TCC with no excess slip, and due to internal cross leaks, have enough residual pressure in the TCC release circuit to open the TCC release pressure switch, causing a code P1887.

P1887的已知原因：

  • 在TCC发布开关信号电路中间歇打开：
    • 疲劳的电线或距离差
    • 缺陷TFP（流体压力开关）
  • 残留的TCC释放压力由于交叉泄漏：
    • Pump bearing seal
    • 涡轮轴
    • 在变矩器内bob游戏怎么下载

格雷格·纳米德is a Sonnax technical specialist and a member of theTascForce®.（技术汽车专业委员会），一批认可的行业技术专家，传输Rebuilders和Sonnax Industries Inc.技术人员。

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相关单位

4T45-E传输 4T40-E传输 4L30-E.传播 4T65-E传输 4T80-E传输 4T60-E传输 4L70-E传输 4L60-E.传播 4L65-E Transmission 4L80-E传输 4L85-E传输

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