Caterpillar TH330b self repair mission

gavztheouch · Mar 25, 2016

Hello, I have a 2005 Cat TH330b forklift and it has been a great machine up until now. Recently it has started giving us some problems, I shall try my best to describe them and hopefully someone may be able to shed some light on my issues.

There are two main problems. One is intermittent and the other is more troublesome so I will start with that.

Problem 1: The hydraulic implement isolator solenoid is showing an under current error. I have traced the wires from the ECU and using a multi meter and a jumper wire I can tell the wires are not broken. My Cat ET diagnostics shows me the isolator switch is working as the ECU is getting a signal from the switch. The only fault I can see is the ECM is only putting out 0.9v to the solenoid, I think this should maybe be 12V?

Problem 2: The gearbox will not engage. It happens maybe 50% of the time. Sometimes we can leave it for and hour or so and it will work again other times it will go in 5 mins and sometimes it will not work all day. My ET diagnostics is showing no errors.

I did notice with the geabox error the cat ET software will show the following values SHIFT LEVER POSTION, DESIRED GEAR and ACUTAL GEAR. When the forklift is working well it will show the SHIFT LEVER POSITION, DESIRED GEAR and ACTUAL GEAR, for example 3R for 3 gear reverse. When it is not working it will only display the SHIFT LEVER POSITION, the important point being the DESIRED gear still stays blank indicating it is not even trying to get into gear?

Many thanks
Gavin

barklee · Mar 25, 2016

gavztheouch said:
Hello, I have a 2005 Cat TH330b forklift and it has been a great machine up until now. Recently it has started giving us some problems, I shall try my best to describe them and hopefully someone may be able to shed some light on my issues.

There are two main problems. One is intermittent and the other is more troublesome so I will start with that.

Problem 1: The hydraulic implement isolator solenoid is showing an under current error. I have traced the wires from the ECU and using a multi meter and a jumper wire I can tell the wires are not broken. My Cat ET diagnostics shows me the isolator switch is working as the ECU is getting a signal from the switch. The only fault I can see is the ECM is only putting out 0.9v to the solenoid, I think this should maybe be 12V?

Problem 2: The gearbox will not engage. It happens maybe 50% of the time. Sometimes we can leave it for and hour or so and it will work again other times it will go in 5 mins and sometimes it will not work all day. My ET diagnostics is showing no errors.

I did notice with the geabox error the cat ET software will show the following values SHIFT LEVER POSTION, DESIRED GEAR and ACUTAL GEAR. When the forklift is working well it will show the SHIFT LEVER POSITION, DESIRED GEAR and ACTUAL GEAR, for example 3R for 3 gear reverse. When it is not working it will only display the SHIFT LEVER POSITION, the important point being the DESIRED gear still stays blank indicating it is not even trying to get into gear?

Many thanks
Gavin

Sounds like you probably know more than i do.... The only comment i can really make is that ive heard that this TH330 machine in particular had some wire harness gremlins and random ecm problems. I know a company with several of these machines and i can distinctly remember them saying they had to replace either the ecm or harness in a few of them. I think they got tired of messing with them and sold every one of them.
The shifting issue sounds like the shifter stalk to me, might be a place to start.

Cmark · Mar 25, 2016

Problem 1. Which error code number are you seeing? With this I can tell you what resistance you should be getting across the coil and maybe some troubleshooting info. Do you have SIS?

Problem 2. It looks like the transmission can be neutralised by either the park brake switch, the service brake switch or the neutraliser switch on the shift lever. You need to monitor those components in the ET status screen while the fault is occurring and see if they are reading correctly.

Nige · Mar 26, 2016

Regarding Problem 1 it's not just a matter of checking continuity of wires in the harness, there will be a procedure to check other things as well. That's why it's important to know what Diagnostic codes you're getting.

A machine Serial Number would help, so that the correct technical information & diagnostic procedures can be located.

gavztheouch · Mar 26, 2016

Thanks for the replies, much appreciated.

Updates.

Problem 1: The error code is MID 039 - CID 0882 - FMI 05 I shall try and get the machine serial number.

Problem 2: It is not the gear shift lever as I have already changed this part with no improvement. The CAT ET also shows the ECM is getting data from the shift lever and it appears correct. As I shift through the gears I can see them updating inside the CAT ET values on my laptop.

Thanks again
Gavin

Nige · Mar 26, 2016

There is a troubleshooting procedure for that Diagnostic Code. I'll get in contact with you and can send it to you by email.

To get the correct Electrical Schematic for the machine you need to get hold of the machine Serial Number (it'll be SLBxxxxx) and find out if it's above or below SLB01500. There is a different schematic depending on if the S/N is above or below 1500.

Cmark · Mar 26, 2016

Here's a quick check for the circuit in question. There's a serial number break on the electrical schematic so without it, it's difficult to progress beyond this, but note the line bolded.

And as for problem two, nobody has (yet) suggested it could even be a problem with the gear shift lever.

System Response:

When this diagnostic code is active, the ECM will turn off the current to the failed solenoid.

Test Step 1. CHECK THE SOLENOID.

A.Turn the disconnect switch and the key start switch to the ON position. Do not start the engine.

B.Disconnect the solenoid with the active diagnostic code from the machine harness.

C.At the machine harness connector for the solenoid, place a jumper wire from contact 1 (wire G962-OR) to contact 2 (wire 352-BU).

D.Observe the status of the CID 0882 FMI 05.

Expected Result:

The CID 0882 FMI 05 remains active. The FMI has not changed and the "05" is still active.

Results:

•YES - The diagnostic code remains active. The jumper wire does not affect the diagnostic code. Proceed to Test Step 2.

•NO - The diagnostic is no longer active. The solenoid has failed.
Repair: The solenoid has failed. Repeat this Test Step "CHECK THE SOLENOID" in order to verify the solenoid failure. Replace the solenoid. Verify that the new solenoid corrects the problem.

Stop.

Test Step 2. CHECK THE HARNESS FOR AN OPEN.

A.Turn the key start switch and the disconnect switch to the OFF position.

B.Disconnect the machine harness connector(s) from the ECM.

C.The jumper wire that was installed in the previous test remains in place.

D.At the machine harness connector, measure the resistance from signal contact J2-2 (wire G962-OR) to contact J2-4 (wire 352-BU).

Expected Result:

The resistance is less than 5.0 ohms.

Results:

•OK - The resistance is less than 5.0 ohms. The machine harness is correct. Proceed to Test Step 3.

•NOT OK - The resistance is greater than 5000 ohms. The resistance measurement is not correct. There is an open circuit in the machine harness.
Repair: The open is in wire G962-OR or in wire 352-BU of the machine harness. Repair the machine harness or replace the machine harness.

Stop.

Test Step 3. CHECK IF THE DIAGNOSTIC CODE REMAINS.

A.Inspect the contacts of the harness connectors and clean the harness connectors.

B.Reconnect all harness connectors.

C.Turn the disconnect switch and the key start switch to the ON position.

D.Operate the machine.

E.Check the status of the CID 0882 FMI 05.

Expected Result:

The CID 0882 FMI 05 is active.

Results:

•YES - The CID 0882 FMI 05 is active. The diagnostic code has not been corrected. The ECM may have failed.
Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, replace the ECM. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

Stop.

•NO - The CID 0882 FMI 05 is not active. The diagnostic code does not exist at this time.
Repair: The initial diagnostic code was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation.

Stop.

Nige · Mar 26, 2016

And as for problem two, nobody has (yet) suggested it could even be a problem with the gear shift lever.

I beg to differ young Skywalker. The OP mentioned in post #5 "It is not the gear shift lever as I have already changed this part with no improvement."

gavztheouch · Mar 26, 2016

Cmark - Well spotted I did not see that bolded part before Maybe this is why it is not putting out 12V to the solenoid. ( I have the service manual and have done these checks) It actually worked when I plugged it all back together after doing the checks but has since stopped working again.

Nige - Thanks, my serial number is CATTH330TSLB01169 (SLB01169) So we are below the 1500 serial break

Cmark · Mar 26, 2016

Nige said:
I beg to differ young Skywalker. The OP mentioned in post #5 "It is not the gear shift lever as I have already changed this part with no improvement."

What I was getting at was that I mentioned three possible causes of the transmission neutralising and gavztheouch answered that point with info that the shift lever had been replaced, but I hadn't even mentioned the shift lever as one of the three possibilities. If "shift lever position" is registering ok on the status screen, as in the op, then it probably isn't at fault so I had already dismissed it as a possibility.

The implement disable solenoid should have a resistance of 10.5 ohms.

Rustyratchet · Mar 26, 2016

I have three th350b's and had a similar problem with going in gear. After changing the handle and the park brake switch with no help,I had Cat come and check it out for me. Well it turned out the torque converter had gone out. It did not just stop working all at once as I thought it would, but actually it worked intermittently for a while. The weirdest part to me was that it made no noise and and no change in feel (vibration ect.) And when it would work it worked normal. Oh and also gave the same codes as yours. I replaced the converter which was clearly broken once I got it out, and all has been good since. I hope it is not your problem for your sake because it was a job to change and probably very expensive if you have it done by someone else. Let us know how this turns out and good luck.

gavztheouch · Mar 28, 2016

Nige, many thanks for sending me the electrical schematic.

Using Cmarks 10.5 ohm benchmark I tested the solenoid and could not get much resistance in the coil. I then bought a 10 ohm 10w resistor from Maplin placed it in the circuit instead of the solenoid and the error code went away. I guess the solenoid coil must have worn out. The parts manual tells me the part number is 200-6210.

Next job will be finding a replacement coil once everyone is back from their easter holidays.

Nige · Mar 28, 2016

I'm showing them available at pretty much any Cat dealer priced around 50 quid.
You do realize that for testing purposes you have six of the same Part Number 200-6210 solenoid valve mounted on the transmission......?

gavztheouch · Apr 4, 2016

Fitted the solenoid valve a couple of days ago and I'm happy to say it has fixed problem 1. I will continue to monitor problem 2 and hopefully it does not come back. Thanks again for everyone's help.

gavztheouch · Apr 11, 2016

Diesel tank sprung and leak a couple of days ago. It ended up being a perished rubber cap on the bottom of the tank.

gavztheouch · Jul 24, 2016

Problem 2 with the gear box has unfortunately not resolved. It seemed to work better after calibration but this may have just been a good run of luck for a few days. Now I am thinking about replacing the forklifts brain (ecu?) Is there anyway of re flashing the unit myself or can I buy a reliable replacement. The other option is to trade it in. Seems a shame as the forklift is otherwise great. I really think all machinery manufacturers should look to design future machines in such a way that computer components can be easily interchanged and configured with a computer yourself at home. Ie you buy a new ecu and then download the specific machine details from the manufactures website.

Caterpillar TH330b self repair mission

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