- A solenoid is an electric valve: the transmission computer energizes it to open, close or regulate the oil that applies clutches and bands, sets line pressure and locks the converter.
- If a shift solenoid fails, the transmission holds certain gears; if the pressure solenoid fails, many units shift harshly, because with no current it sets maximum pressure.
- A solenoid code isn't always the solenoid: carmakers also blame connectors, harnesses, voltage, water, debris, valve body wear or software.
- There's no universal resistance value, and a click doesn't prove it works: use your transmission's procedure and specs.
- Carmakers don't repair solenoids, they replace them; on the Chrysler 41TE, 42RLE and 62TE the solenoid pack is replaced as a unit.
If your transmission won't upshift, holds one gear, shifts harshly or the scan tool shows a code between P0740 and P0986, the solenoid is a suspect, but not always the culprit. Here is what each type of solenoid does, the symptoms carmakers attribute to it, which gear your transmission holds in limp mode, how it's tested, whether it can be repaired and which TSS solenoid your transmission takes.
What is a transmission solenoid?
It's an electric valve mounted on or next to the valve body. As Chrysler's Spanish-language manual explains, when a solenoid is energized it opens or closes a fluid passage, and the result is that a clutch or band applies or releases. The transmission computer decides when to energize it based on speed, throttle and gear.
Don't confuse it with the shift interlock solenoid, which locks the lever in Park, or with the starter solenoid, which cranks the engine.
Types of solenoids
- On/off shift solenoids: open or close an oil passage to the shift valves. Examples: the 4L60E (A and B), 4R70W, 01M, 09G and RE4F03.
- Pressure control solenoids (EPC, PCS or line pressure): regulate line pressure. In many units, such as the 4R70W, RE4F03, 09G and the 46RE governor, no current means maximum pressure, so an electrical fault usually causes harsh shifts rather than slipping.
- Torque converter clutch (TCC or lock-up) solenoids: apply the converter clutch; they can be on/off or pulse-width modulated (PWM).
- Linear or variable-force solenoids: regulate each clutch's pressure, as in Honda units, the 09G and the 6R80.
- Solenoid packs: on the Chrysler 41TE, 42RLE and 62TE they come as an assembly with pressure switches that, according to Chrysler, can only be serviced by replacing it.
- Inside a module: on the GM 6T40 and 6T70, DSG units and Nissan CVTs, the solenoids sit inside the module or valve body, and the carmaker replaces the assembly. The PowerShift has no shift solenoids at all: it uses electric motors.
Symptoms of a bad transmission solenoid
What you feel depends on which solenoid fails. Here are examples from the carmakers themselves:
| Symptom | What the carmakers say |
|---|---|
| Won't upshift or holds one gear | On the 4R70W, if both shift solenoids fail off, it holds 2nd gear only (Ford); on the 09G, if N88 fails, 4th to 6th are no longer available (VW) |
| Harsh shifts | If the pressure solenoid fails off, pressure goes to maximum and shifts are harsh (Ford on the 4R70W, VW on the 09G) |
| Slipping or lack of power | If the pressure solenoid fails on, pressure drops to minimum and the computer limits engine torque (Ford, 4R70W) |
| No lock-up, or stalls when braking | If the converter clutch solenoid fails on, the engine stalls in 2nd at idle with the brake applied; if it fails off, the converter clutch never engages (Ford, 4R70W) |
| Missing gears | On the GM 6T40, a non-working pressure control solenoid leaves no 1st, no 2nd and 6th, or no reverse, 3rd and 5th, depending on which one (GM, US) |
| Check engine light | The computer monitors the circuits constantly (Chrysler checks them every 10 seconds), but some performance codes don't turn on the light (GM) |
Limp mode: which gear your transmission holds
When the computer detects a serious electrical fault, it leaves the transmission in a fixed gear so you can still move. Which one depends on the transmission:
| Transmission | Limp mode |
|---|---|
| 41TE and A604 | P, R, N and 2nd (Chrysler) |
| 62TE | 3rd |
| 42RLE | Neutral if the fault sets above 35 km/h (22 mph); limp mode below that (Chrysler) |
| RE4F03 (Versa, March and Tsuru) | 3rd (Nissan) |
| 01M (Jetta Mk4) | 3rd |
| 09G | Pulls away in 3rd; if already in 4th, 5th or 6th, it holds that gear until you select N or turn the engine off (VW) |
| DSG | Only half the gears (VW) |
| 4L60E | 2nd if it loses the speed signal; 3rd if the shift solenoid B circuit fails (GM) |
| 6R80 | 3rd or 5th (Ford) |
| 4F27E (Focus and Mazda 3) | 3rd, according to ATSG |
On Volkswagens, the dash warns with an emergency-mode message: it's a warning, not a diagnosis. We explain it in why an automatic transmission won't shift.
Is it the solenoid or something else?
A solenoid code isn't always fixed by replacing the solenoid. In their bulletins, carmakers also blame:
- Connectors and internal harnesses: on the 6R80, Ford fixed 5th-gear starts by replacing the lead frame, with no new solenoids; on the 4R70W, a faulty case connector left the solenoids without power (Transmission Digest); and on the Explorer with the 5R55W, the code came from water in the connector (US bulletins).
- Harness corrosion: on a 2003 Caravan, it made the transmission default to 2nd gear (US).
- Low voltage in the solenoid power supply, or a backed-out terminal in the connector (GM).
- Debris at a valve body orifice (GM, 4L60E with code P0756) or water in the fluid (GM, 6L80).
- Valve body wear: on the 4R70W, 01M, 09G and 5R55W, worn bores steal pressure, and a new solenoid doesn't fix it.
- Software: GM and Honda fixed some codes with a reprogram.
For example, according to Chrysler, on the 41TE code P1776 points to a valve in the valve body, not to the solenoid pack.
Solenoid trouble codes
| Code | What it means |
|---|---|
| P0740 to P0744 | Torque converter clutch (TCC) solenoid |
| P0745 to P0749 | Pressure control solenoid A (P0775 to P0779 is B, and P0795 to P0799, C) |
| P0750 to P0774 | Shift solenoids A to E, five codes each |
| P0960 to P0971 | Pressure control solenoid A to C control circuit |
| P0972 to P0986 | Shift solenoid A to E control circuit |
| P2757 to P2764 | Torque converter clutch pressure control solenoid, on newer units |
The letter depends on the brand: on the Chrysler 41TE and 42RLE, P0750 is the LR solenoid; on Fords, shift solenoid A; and the 46RE doesn't use P0750 at all (its overdrive solenoid code is P0753). Also, a circuit code points to an electrical fault, but a performance code, such as GM's P0751, can also come from a valve, debris or a clutch. Sun Transmissions explains codes P0740, P0741, P0750, P0755, P0760 and P0974.
How to test a transmission solenoid
This is the order the carmakers' manuals follow:
- Read the codes with a scan tool and check the freeze frame. GM says not to keep replacing parts if the system passes the verification.
- Check the fluid level and condition: Honda drains it through a strainer, and if it has metal debris or a lot of clutch material, it says to replace the transmission.
- Command the solenoid with the scan tool and listen to or measure its response.
- Check the circuit from the computer's connector, then the solenoid; wiggle the harness to find intermittent connections.
- Run a pressure test before condemning a solenoid pack or the valve body.
There's no universal resistance value. On the 4R70W, according to Ford, the shift solenoids measure 20 to 30 ohms and the EPC 2.5 to 5.7; on the Versa's RE4F03, according to Nissan, shift solenoid A measures 20 to 30 and B 5 to 20; on Hondas, 12 to 25 for the shift solenoids and 3 to 10 for the linear ones; and on the 01M, according to ATSG, 55 to 65 for the shift solenoids and 4.5 to 5.1 for the pressure ones. Use your transmission's manual values.
And a click doesn't prove it works: in Honda's procedure, if the solenoid clicks and the code comes back, the next step is to repair the shift valve or replace the transmission. The click only tells you the plunger moves, not that it regulates pressure properly.
Can a transmission solenoid be repaired?
Carmakers don't repair it: they replace the solenoid, the solenoid pack or the module. What can be repaired is around it: terminals and connectors, the internal harness, filter screens, the fluid and cooler, and valve body wear. Some specialist shops rebuild certain solenoids on the bench, such as the 09G linear solenoids; for that, TSS carries the 09G solenoid repair bushing.
If you clean them, don't use gasoline: Chrysler forbids it in its manual, and transmission specialists advise against putting electrical parts in a parts washer. And after replacing solenoids, the computer needs a relearn: GM, Chrysler, Ford and VW all call for it.
Which TSS solenoid does your transmission take?
Before you order, check the year, the connector and your part number: there are versions by year, such as the 4R70W's hard or soft harness or the 09G's 1-inch or 3/4-inch solenoids, and on the 09G each solenoid goes in its own position.
TSS solenoids
The TSS catalog has shift, pressure control, converter clutch and linear solenoids, solenoid packs for Chrysler units, complete sets and harnesses for GM, Ford, Chrysler, Volkswagen, Nissan, Honda and Toyota transmissions. In the US, Sun Transmissions carries shift solenoids, pressure control solenoids and TCC solenoids; in Mexico, Transmisiones Veinte 07 has its transmission solenoid collection.
TSS is an aftermarket brand with OEM-comparable quality and quality control on every product. You can buy it from our authorized distributors: in the United States from Sun Transmissions, and in Mexico the full TSS catalog at Transmisiones Veinte 07.
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