Isuzu SUV Forum banner
1 - 4 of 4 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter · #1 ·
Hi,

my Trooper 93 SOHC 3.2l with an 4L30E transmission shows the transmission trouble code 33 and goes in to limp mode. Not immediately when i but the gear shift in drive, only randomly if I slow down. In the transmission manual say that the pressure (force motor) solenoid is shorted to battery. So I have replaced the wires between the computer and the contector. Still the same problem.

I opened the transmission and tested the pressure solenoid and the wiring inside it works good. I connect the solenoid to a 12V battery.

I but everything together and tested the Voltage at the computer between pin 40 and 41 but there are only 4Volt and flowing 0.9AMP put it needs 1-1.5A.

I brought the computer to two electrician to test and both guarantied that the computer is, good.

Now I don't know anymore what could be the problem.

My question is: Does the throttle position sensor send a signal to the pressure solenoid from ECM through the TCM and can be this the problem for the low voltage?

It would be great if somebody know the answer thanks!
 

·
Registered
Joined
·
11,874 Posts
The Force Motor ("Pressure Control Solenoid") operates at 12 Volts @ 600Hz, it is similar to a Pulse Width Modulated (PWM) solenoid. The signal is a string of positive going pulses with a variable duration. You can't get an accurate voltage measurement using a DC volt meter and you can't adequately test it by applying a DC voltage. You potentially can destroy it by applying a DC voltage.

At minimum throttle position the Force Motor signal duty cycle is maximum resulting in current flow of around a 1.1 amps, which is typically the maximum control current. At maximum control current the Force Motor exhaust port is fully open and the discharge port is fully closed resulting in minimum throttle signal hydraulic pressure. Conversely, at maximum throttle position the duty signal is minimum and current flow is approximately 100 milliamps, at minimum current the Force Motor exhaust port is fully closed and the discharge port is fully open resulting in maximum throttle signal hydraulic pressure. Therefore, throttle signal hydraulic pressure is being controlled by the current flowing (0.1 to 1.1 amps) through the Force Motor (solenoid coil) which is dependent on the duty cycle of signal. The throttle signal hydraulic pressure controls the pressure regulator valve which in turn controls the clutch pack pressure.

Force Motor DTC 33 is set if the current in the control circuit is greater than 1.5 amps on a Type 1 TCM.

If the Throttle Position Sensor is adjusted and working correctly my best guess is defective TCM because this problem has been reported before and TCM replacement fixed the problem.
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #3 ·
Hi thanks a lot.

Today I have tested the TPS and it works all good.

I will bring the Truck to an electrician today. Hope he can find the problem and maybe can fix it.

I will let you know what was the problem.
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #4 ·
Hi,

want to share the solution for my problem.

First of all I made a mistake checking the Force Motor Solenoid. I have test it with 12Volt and it worked. But i had to test it for the AMP to see if the coil winding is still good
The way I test it looks like this.

You need a digital volt meter with an OHM function..

basicly.. you are going to hook your amp meter in the circuit you hook directly to the battery for 3 to 7 SECONDS.. while you are monitoring the amp draw of the coil winding as it heats up…

positive battery… clip… test lead………… coil winding positive..

negative battery.. clip.. test lead.. amp meter.. test lead.. coil winding negative..

this is a 3 to 7 second test only..

it allows you to monitor the amp draw of the coil winding.. it gives a true look at the coil windings… if they are leaking.. you will see an issue within seconds..

there does seem to be a diode in the winding.. if youhook up backwards.. you will blow the diode and ruin the coil .

regards
David
 
1 - 4 of 4 Posts
Top