Transmission and drivelineModel years not statedTrade technical source
4L60-E / 4L65-E TCC regulator valve bore wear (P1870 converter clutch slip)
GM 4L60-E, 4L65-E and 4L70-E units with PWM or EC3 converter clutch control (no model years for these trucks stated)
FaultCrate・4L60-E / 4L65-E TCC regulator valve bore wear (P1870 converter clutch slip)
This often sets code P1870 and/or P0894 because of excess TCC slip.
Continuous oscillation of the regulator valve in PWM and EC3 units wears the bore over time so that apply pressure exhausts.
What to do
- As the regulator bore wears, the duty cycle needed to keep slip in range increases.
- TCC problems can often be spotted before they set codes by monitoring duty cycle with a scan tool.
- Per Sonnax, a worn TCC regulator valve bore is restored by installing its TCC regulator and isolator valve kit 77754-04K or 77754-03K.
If left
- This is a primary cause for TCC-related slip code P1870 and overheated converters.→ torque converter
- The exhausting apply pressure also lowers line pressure, which can result in burnt clutches.→ transmission clutches
Caution
- Blocking the regulator valve with a pump slide spring can eliminate these codes but not the bore wear that caused them.
- Never block the TCC regulator or isolator valves.
Applies to
- In GM 4L60-E, 4L65-E and 4L70-E units, oscillation of the OE valve severely wears the TCC regulator valve bore and lets regulated converter apply pressure exhaust.
See the evidence (3 documents, 10 passages)
| Document | Publisher | Date |
|---|---|---|
| [1]TCC Regulator & Isolator Valve Kit 77754-03K ↗ | Trade technical sourceSonnax (product page) | — |
| [2]20 Years Later: What's New with 4L60-E PWM Modifications ↗ | Trade technical sourceSonnax | 2014-12-09 |
| [3]All Over the Map: Attacking 4L60/E Burnt 3-4 Clutches with Confidence ↗ | Trade technical sourceSonnax | 2018-06-06 |
Applies toIn GM 4L60-E, 4L65-E and 4L70-E units, oscillation of the OE valve severely wears the TCC regulator valve bore and lets regulated converter apply pressure exhaust.
In GM 4L60-E, 4L65-E and 4L70-E units, severe wear of the TCC regulator valve bore is caused by oscillation of the OE valve allows regulated converter apply pressure to exhaust.— [1] product description
Why it happensContinuous oscillation of the regulator valve in PWM and EC3 units wears the bore over time so that apply pressure exhausts.
A common problem with PWM and EC3 units is caused by continuous oscillation of the regulator valve, which creates bore wear over time that allows critical apply pressure to exhaust.— [2]
First signsThis often sets code P1870 and/or P0894 because of excess TCC slip.
This often results in the setting of code P1870 and/or P0894 due to excess TCC slip.— [2]
If leftThis is a primary cause for TCC-related slip code P1870 and overheated converters.
This is a primary cause for TCC-related slip code P1870 and overheated converters.— [1] product description
If leftThe exhausting apply pressure also lowers line pressure, which can result in burnt clutches.
Exhausting apply pressure also diminishes line pressure, which can result in burnt clutches.— [1] product description
How to confirmAs the regulator bore wears, the duty cycle needed to keep slip in range increases.
as the regulator bore wears, the duty cycle required to keep slip in the appropriate range increases.— [2]
How to confirmTCC problems can often be spotted before they set codes by monitoring duty cycle with a scan tool.
You often can spot TCC problems before they trigger codes by monitoring duty cycle with a scan tool.— [2]
CautionBlocking the regulator valve with a pump slide spring can eliminate these codes but not the bore wear that caused them.
Transmission builders quickly realized they could eliminate these codes (but not the bore wear that caused them) by blocking the regulator valve with an inner pump slide spring from a 700-R4— [2]
CautionNever block the TCC regulator or isolator valves.
Never block the TCC regulator or isolator valves.— [3]
RepairPer Sonnax, a worn TCC regulator valve bore is restored by installing its TCC regulator and isolator valve kit 77754-04K or 77754-03K.
If the TCC regulator valve bore is worn, the only way to restore the valve bore and prevent pressure loss is to install Sonnax TCC regulator and isolator valve kit 77754-04K (OE apply rate) or 77754-03K (increased apply rate).— [2]
Put together by FaultCrate from public records and technical documents. The cause and the repair are for the workshop to decide with the vehicle in front of it. Counts are records, not failure rates.
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