P0900 – Clutch actuator -circuit open
Last Updated 2016-05-03
Automobile Repair Shop Owner
|Code||Fault Location||Probable Cause|
|P0900|| Clutch actuator -circuit open |
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|Wiring, clutch actuator, ECM/PCM/TCM|
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Table of Contents
- What Does Code P0900 Mean?
- What are the common causes of code P0900 ?
- What are the symptoms of code P0900 ?
- How do you troubleshoot code P0900 ?
- Codes Related to P0900
- Get Help with P0900
What Does Code P0900 Mean?
OBD II fault code is defined as “Clutch Actuator – Circuit Open”, and is set when either the PCM (Powertrain Control Module), or TCM Transmission Control Module) detects an open circuit in the clutch actuator’s control circuit. The TCM interprets the actuator output voltage as it engages and disengages the clutch, along with that of the clutch stroke/movement sensor.
Much like fully automatic vehicles, the TCM on a SAT (Semi-automatic) vehicle uses information from a variety of sensors, such as the throttle position, engine speed, engine load, and others to calculate the correct moment when to initiate a gear change.
Gear changes are accomplished by a command from the TCM to energize the clutch actuator to release the clutch; after which various actuators inside the transmission disengage the current gear, and depending on current operating conditions, engage the next higher or lower gear ratio. All of this happens much faster than a human driver could change gears, and in most applications, gear changes are as smooth and seamless as on any fully automatic transmission.
Some types of actuators involve solenoid-type mechanisms to operate a clutch master cylinder in which power is transferred by brake fluid, such as in some Toyota models, while still other designs use electronic sensors, pneumatic and or hydraulic actuators, or a combination of sensors and different types of actuators that are controlled by microprocessors.
Regardless of the design though, the purpose of all clutch actuating systems is to improve the driving experience by removing the need for manual clutch operation by the driver. Computer-controlled clutch actuating systems work particularly well in dual clutch systems where one clutch controls gear changes of even-numbered gear ratios, and a second clutch that controls gear changes of odd-numbered ratios.
The image below shows one example of a clutch actuator. This particular unit is from Smart car, and uses an electric motor to rotate a crank-type mechanism to activate the clutch. Note that this is only one example of a clutch actuator; there are many other, different designs in use today.
What are the common causes of code P0900 ?
A common cause of code P0900 is the failure of the selector switch on the gear selector, but there are several other possible causes as well, such as-
- Open circuits caused by damage to wiring.
- Open circuits caused by corrosion of electrical connectors.
- Loss of ground.
- Internal electrical failures in actuator motors/solenoids.
- Failures of clutch motion/travel sensors.
- TCM failures, but this is rare, and the fault must be sought elsewhere before any control module is replaced.
What are the symptoms of code P0900 ?
As a rule, the main symptom of code P0900 is the non-engagement of any gear, but depending on the application, there may be other symptoms present besides an illuminated CHECK ENGINE light (which may, or may not illuminate) and a stored trouble code. Other possible symptoms may include-
- Engine may stall when the control system fails during driving.
- In some applications, the engine will not crank as a safety precaution when code P0900 is present.
- In some cases, the transmission may enter into a “limp” mode.
- In some cases, the transmission may be stuck in one gear, without entering “limp” mode.
How do you troubleshoot code P0900 ?
NOTE #1: Diagnostic, repair, and replacement procedures are for the most part make and model specific, meaning that apart from a code scanner and a digital multimeter, a good repair manual is an essential item when attempting to diagnose and repair code P0900.
NOTE #2: The design of clutch actuators and their control circuits vary widely between manufacturers, as do the actual working of different actuator designs. For this reason, it is important to have a repair manual and wiring diagram for the application being worked on at hand, since the code-setting parameters, diagnostic/repair procedures, and replacement procedures are often unique to many applications and designs.
NOTE#3: Some systems require that the actuator has an adequate supply of brake fluid. Low brake fluid levels can mimic the symptoms of code P0900, so consult the manual to locate the brake fluid reservoir. Bear in mind that a low fluid level can set code P0900 on some applications, so make sure that on fluid operated systems the fluid level is up to the mark before starting an electrical diagnosis.
Once the presence of code P0900 is confirmed with a scan tool, and you have ascertained that the system is not fluid-operated, record all freeze frame data for future reference in the event that an intermittent fault is identified later on.
NOTE: It is entirely possible that one, or more of closely-related codes P0901, P0902, and P0903 may be present along with P0900.
Clear all codes, and consult the manual to determine the color-coding, location, and routing of the control circuit wiring. Perform a thorough visual inspection of all associated fuses, relays, and wiring to check for damaged, broken, pinched, or corroded wiring and connectors. Repair as required, but pay particular attention the selector switch on the gear selector, as well as the battery condition and voltage.
Clean and retighten battery terminals as required, and consult the manual on the correct test procedure(s) for the selector switch, or any other switches related to the clutch actuator. Replace any switches that do not conform to manufacturer’s specifications.
If the switch(es) appears to be fully functional, disconnect all relevant control modules, and perform ground, power supply, and continuity checks on all wiring. Also, be sure to perform an amperage draw test on the actuator motor/solenoid, as well as on the actuator position sensor. These components form part of the control circuit, and must be tested along with everything else. Repair, or replace components as required. Retest the system to see if the code returns, or if repairs were successful.
NOTE: The setting parameters of code P0900 are different for almost all applications, so be sure to consult the repair manual for the exact resistance, amperage, and reference/system voltages/values.
If all values fall within specification, consult the manual on the correct procedure to apply power directly to the clutch actuator mechanism, paying due regard to the required voltage, which will be stated in the manual. If the mechanism does not respond, check all connections and the ground. Also be sure to check the mechanism for continuity and resistance before applying power directly.
If the mechanism works, test it repeatedly to check for intermittent faults or signs of overheating. Normal operating temperatures will be stated in the manual. If the unit overheats, or works intermittently, replace it. Reconnect all wiring and control modules, clear all codes, and operate the vehicle with a scan tool connected to see if the code returns.
WARNING: On some applications, replacement of the actuator mechanism requires reprogramming, and/or integration with the TCM or PCM, or both. It is critically important to follow the correct procedures during removal and installation to prevent damage to clutch, or clutch actuator parts and components. Always consult the manual on the correct installation/reprogramming/integration procedure(s).
If the code returns after a test drive, there is likely to be an intermittent fault present, which you may have to allow to worsen before an accurate, and definitive repair can be made.
Codes Related to P0900
- P0901 – Relates to Clutch Actuator Circuit Range/Performance
- P0902 – Relates to Clutch Actuator Circuit Low
- P0903 – Relates to Clutch Actuator Circuit High
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Code P0900 is a common problem on several Toyota models, in particular Corolla Verso, Auris, Aygo, and Yaris models.
The most common symptoms of code P0900 on these Toyota models are-
•Being stuck in neutral
•Slipping out of gear
.Transmission warning light on the dash illuminates
•Complete failure of the actuator unit.
With the mentioned Toyota models the most common cause are the following
• The actuator fails to self-adjust as the clutch plate wears, i.e., the clutch plate gets progressively thinner as it wears. The actuator has a fixed amount of travel, and when it fails to adjust itself to the additional distance it needs to travel to compensate for the wear in the clutch, code P0900 can be set.
This can sometimes be fixed by having the clutch actuator recalibrated, but only Toyota dealers should do this, since the procedure is done with equipment and software that is generally not available to the independent repair industry. However, the amount of wear on the clutch may be too much for the actuator to be recalibrated, in which case the clutch must be replaced.
• Another possibility is that the sensors that monitor the position(s) of the gears in the transmission have failed, or are in the process of failing. When this happens, the TCM (Transmission Control Module) gats invalid readings. What this means is that the TCM “thinks” the transmission is in a particular gear, when in fact, it is in another gear.
This can be confirmed, or eliminated as a possibility by having the transmission scanned for specific trouble codes, but the repair is a highly technical affair, and should be left to a Toyota dealer. I do not recommend that you attempt to replace the range sensors yourself, or have an independent shop do it since only the dealers have the correct software to diagnose, and recalibrate the system after a repair.
• The last possibility is that the actual selector mechanism- the parts that move the gears around in the transmission- are sticky. This is not a DIY repair job, but good results can sometimes be had by replacing the transmission oil. The selector shaft is located in an area of the transmission casing that is relatively poorly lubricated, so new oil could free sticky components.
I hope this helps you find the problem.
hI ALL, I am struggling to have my car moving again after I replaced the clutch kit and then as the car refused to move or do any action , Technician thought of the Electrical actuator , so I bought a new Actuator . installed in the car but again the car does not move at all, I have ended up to change the TCM but even after a bought a new TCM installed to the car , the car still with the same fault : P0900. Electrical actuator circuit open , I have checked and measured the Voltage at the Actuator plug , it was less than 9V , so I dont know if there is a wiring damage issue or some thing else ,
please kindly guide me what is wrong with my car and how can track this problem and sort it out.
Does anyone know what voltage is used to actuate the clutch actuator I’m getting 5volts leaving the TCM and going to the actuator and it’s not working
Should it be 12 volts
I replaced TCM still get 5 volts
Hello Nabil. The voltage you are seeing is proper seems how it is a reference voltage wire. Reference wires have 3- 5 volts. Computer input lines need lower impedance to avoid damaging the tcm or ecu. Hope that answers your question.
I’ve installed a new clutch actuator 3981000066.when I received and put it on it was retracted and fit on just fine .I adjusted it like the instructions stated and hooked up the electrical connector, started the car and the part extended and tried to opperate but that was it now it still won’t function at all and it will not retract back into place so I can install it again. What do I do next help??? The car is a 2008 Smart for two passion convertible
Joe!!! Hi k hace they same code i just change the crankshaft seal. I just went to a friend shop yestarday And they toldme the open circuit means something is disconnected in the gearbox sensor i think! Because i have take out the gearbox. And disconnect 3 arneses
The gear selector
And one bulb/ sensor
Mi car run & drive fine!
Also y earse the code but they comes again
Also i read And some friend toldme you have yo calibrate the actuator before you service the box And for me Thats make sence.
How you fix your problem?
Smart 451 petrol 2015
I have a 2013 smart 451 and got a p0900 code that i can’t erase, when i erase it with my diagnostic tool it just comes straight back on? ….the car drives and shifts gears as normal….is it ok to use the car?
I would say that you have a dead open or short circuit problem that is giving you the DTC. From your description of the vehicle’s drivability, you MIGHT be able to drive the vehicle without creating any additional problems, but I wouldn’t count on it. The problem is that the actuator isn’t giving proper feedback to the ECM, which means that the ECM has no idea if it’s working properly or not. Even minor timing issues in the clutch actuator may cause problems long-term.
I found a step-by-step tear-down that someone posted (http://www.smartcarofamerica.com/forums/f369/clutch-actuator-maintenance-instructions-40960/) that might help. Apparently this model has issues with water entry, which can cause corrosion and circuit problems, as well as seizing and sticking problems of the actuator itself. The former, if present, would definitely cause a circuit malfunction DTC.
I hope this helps.
I forgot to mention that I disconnected the battery (both terminals) to charge it up because it had been standing for about 4 months.
Is it possible that the engine has to re-program itself (driven around a bit) because I disconnected the battery?
The car has only done 3800 miles from new and never driven in the rain so I don’t think It could be a water entry issue.
Just want to explore easy fixes before I attempt to remove the actuator.
thanx for your help.
Hmm, with so little mileage, I would seriously doubt corrosion as an issue, then. The problem is that the ECM is seeing a circuit malfunction. I wonder if, even for a moment, you overloaded a circuit or reverse-connected the battery and burned something out? (If there was a recalibration thing to run, you’d probably get an informational code or no code at all.)
I’m thinking you’ll have to still go over the wiring to be sure no rodents have gotten into the wiring, because they’ll chew through anything that’s in their way of making a nest. Stored vehicles are notorious for rodent-related electrical problems.
what could be the cause of this error? I have got toyota auris 1.6 2009 semi auto