Code 24 after warmed up

[Maxo]

I'm having an issue with my transmission where by my power light doesn't flash when I start my car in the morning but if I restart the car after I've driven it for ~10min the power light does flash. I've checked the codes and it's a 24 duty solenoid C. Other than that, the transmission shifts great and the fluid is clean.

One might assume that something is happening when the fluid warms up but that's not definitive. Any ideas?

[svxistentialist]

That's a hard one to call, but there are two things come to mind you might look at; first, try the easiest. Solenoid C controls the rear clutch in your model gearbox, so check that there is not a fuse in place in the fuse board under the hood. [I'm assuming your car is AWD?]

If it is not wiring or a fuse at the fuse board, then you next have to look at solenoid C itself. You have to drop the sump to see this, but you don't have to take the box out, which is a bonus. You would be looking for loose or damaged wires, or possibly pinched wires that could cause an intermittent electrical signal.

If you see nothing glaringly obvious, then maybe your C solenoid is gone bad and you need to change it.

Joe

[Maxo]

I started the car up today at lunch and didn't get the flashing power light, which wasn't any surprise. However, after driving ~15min then stopping and restarting the car shortly thereafter the power light didn't start flashing as I expected! Now I'm really confused as to what would be causing an intermittent error code.

Since I recently had the front differential replaced so could this just be the awd clutches re-seating themselves? All the work I did myself and I can say with a high degree of certainty that I put things back together correctly.

On a side note: I've had solenoid c problems before but the only thing from that transmission still in my car is the front differential and TC(after flush).

[svxistentialist]

Well Maxo, since the error code that comes up is the Solenoid C code, and this solenoid distributes power front to rear, then maybe it is possible the new differential is affecting the readings.

Are you finding the rear wheels "grabbing" if you turn sharp on gravel or grit?

What you can try is find a big enough empty car park and perform the figure of 8 maneuver which is a help in bedding and smoothing the clutches.

Joe

[oab_au]

Originally Posted by Maxo

I started the car up today at lunch and didn't get the flashing power light, which wasn't any surprise. However, after driving ~15min then stopping and restarting the car shortly thereafter the power light didn't start flashing as I expected! Now I'm really confused as to what would be causing an intermittent error code.

Since I recently had the front differential replaced so could this just be the awd clutches re-seating themselves? All the work I did myself and I can say with a high degree of certainty that I put things back together correctly.

On a side note: I've had solenoid c problems before but the only thing from that transmission still in my car is the front differential and TC(after flush).

Yes it can't be a complete failure or the light would flash all the time you start it. But it has to .be with the C solenoid, or it would not give the code. So either as Joe says it could be a intermittent short/open in the wiring, or the solenoid is sticking. No real joy, but it should only be in the rear section to remove.

Harvey.

[Maxo]

Well, the problem seems to have disappeared for now. I did some tight figure 8's in a vacant parking lot which may have helped. I didn't notice any grabbing of the tires during the execution of these maneuvers.
So I think I may be in the clear. The person who had this transmission before me never had any issues with the solenoid c so I'm hoping it was just the clutches or something temporarily stuck.

After having the car up on jack stand and dropping the transmission, doing the tail housing should seem like cake... Although I'd rather not have to deal with it.

[Maxo]

Guess I'm not in the clear. Power light began flashing again, checked the codes and same as before 24 - duty solenoid c.

What sort of tests can I run just to rule out things prior to having to take the tail housing off?

[oab_au]

Originally Posted by Maxo

Guess I'm not in the clear. Power light began flashing again, checked the codes and same as before 24 - duty solenoid c.

What sort of tests can I run just to rule out things prior to having to take the tail housing off?

Not a lot Max. A code 24 has to be confined to the C solenoid itself or the wiring to it. The TCU can not detect anything from the C solenoid on, like the clutch plates or the transfer valve gear.
You could check the wiring at the plugs that connect the transmission, to see if all the wires are pushed in tight. Otherwise the wiring inside the tail section.

Harvey.

[Maxo]

I checked for the distinct sound made by solenoid c by placing the gear selector in D then turning the ignition to the on position. My girlfriend has a SVX as well. She did the same test so I knew exactly what to listen for. I heard absolutely nothing. I examined the wiring, specifically the connections, and everything looked satisfactory.
I also checked the ohms on the connector to the TCU and got a reading of 11.9 However, I'm not sure if I was using the meter correctly or how accurate that meter is. Shouldn't the correct reading be between 13 and 15 ohms? So what does a reading that's out of that range indicate?

It has become increasingly likely that solenoid C has either failed either that or the wiring to solenoid c inside the housing had been pinched or has become disconnected. That solenoid was supposedly in good condition which is why I left it in place when I had the transmission out. I'm not looking forward to taking that exhaust down again... It's such a pain when using jack stands!

[oab_au]

Originally Posted by Maxo

I checked for the distinct sound made by solenoid c by placing the gear selector in D then turning the ignition to the on position. My girlfriend has a SVX as well. She did the same test so I knew exactly what to listen for. I heard absolutely nothing. I examined the wiring, specifically the connections, and everything looked satisfactory.
I also checked the ohms on the connector to the TCU and got a reading of 11.9 However, I'm not sure if I was using the meter correctly or how accurate that meter is. Shouldn't the correct reading be between 13 and 15 ohms? So what does a reading that's out of that range indicate?

It has become increasingly likely that solenoid C has either failed either that or the wiring to solenoid c inside the housing had been pinched or has become disconnected. That solenoid was supposedly in good condition which is why I left it in place when I had the transmission out. I'm not looking forward to taking that exhaust down again... It's such a pain when using jack stands!

Yes Max I can't see you not pulling the back off. The resistance reading at the TCU would be OK. The buzzing is also from the A solenoid, so it isn't a strict clue.

The wire at the solenoid would be the most likely.

Harvey.

[Trevor]

Originally Posted by Maxo

I checked for the distinct sound made by solenoid c by placing the gear selector in D then turning the ignition to the on position. My girlfriend has a SVX as well. She did the same test so I knew exactly what to listen for. I heard absolutely nothing. I examined the wiring, specifically the connections, and everything looked satisfactory.
I also checked the ohms on the connector to the TCU and got a reading of 11.9 However, I'm not sure if I was using the meter correctly or how accurate that meter is. Shouldn't the correct reading be between 13 and 15 ohms? So what does a reading that's out of that range indicate?

It has become increasingly likely that solenoid C has either failed either that or the wiring to solenoid c inside the housing had been pinched or has become disconnected. That solenoid was supposedly in good condition which is why I left it in place when I had the transmission out. I'm not looking forward to taking that exhaust down again... It's such a pain when using jack stands!

Maxo,

You appear to have established that all is electrically sound from the point from where you checked resistance, including the wire at the solenoid. The specified resistance is between 9 and 15 ohms, so that your measurement is well within tolerance.

The system is capable of indicating faulty armature travel, and it could be that something is casing this to be intermittent. Full constant full travel results in only front wheel drive. If the valve does not close properly, full all wheel drive will not be possible. Therefore a condition of partial travel, can do no damage.

I suggest you relax for a bit and see if things settle down. If not report back with exact symptoms.

[b3lha]

From looking at the TCU programming, I think that there are two circumstances that will cause error code 24.

a) The duty cycle is in the "on" phase, but the solenoid is not open.
b) The duty cycle is in the "off" phase, but the solenoid is not closed.

One or both of these events has to occur 8 times in succession (which only takes a moment, but the goal of this is to prevent false readings).

I don't really know anything about the actual workings of the gearbox, but my best guess is that or your solenoid has some dirt in it and sometimes does not fully open or close. Either that or there is a problem in the windings of the solenoid, or the wiring leading to them, that causes the TCU to sometimes infer its position incorrectly.

For an intermittant problem like this, I would leave it alone and wait for it to get better or worse. If it gets better then you have nothing to worry about, if it gets worse then it will be easier to diagnose.

[Trevor]

Phil,

You have confirmed my suggestions and I am particularly interested to note that you refer to two separate mechanical conditions, in both on/energised and off/de-energised states. Have you been able to establish that two separate signals are involved?

It has always intrigued me that the according to the manuals, the system is able to record faulty solenoid movement as well as electrical malfunction. The only way I can envisage this being achieved, is by sensing the level inductance. If there are two signals involved, a high and low sate of inductance must be separately registered. Very clever indeed.

Cheers, Trevor.

[b3lha]

Originally Posted by Trevor

Phil,

You have confirmed my suggestions and I am particularly interested to note that you refer to two separate mechanical conditions, in both on/energised and off/de-energised states. Have you been able to establish that two separate signals are involved?

It has always intrigued me that the according to the manuals, the system is able to record faulty solenoid movement as well as electrical malfunction. The only way I can envisage this being achieved, is by sensing the level inductance. If there are two signals involved, a high and low sate of inductance must be separately registered. Very clever indeed.

Cheers, Trevor.

It's hard to understand, but I think there is just one signal to check the solenoid state. I don't know which position, closed or open, the signal represents. Furthermore, I have no idea how the state is detected. Perhaps, as you say, it is by measuring inductance.

To be absolutely precise for you: If we assume the signal indicates "closed/not closed", then the error condion is that (a) The solenoid is energised but the signal says "closed", or (b) The solenoid is not energised and the signal says "not closed". Obviously if the signal indicates "open/not open" then the opposite applies.

Phil.

[Maxo]

The issue with solenoid c has become more of a regular occurrence now. The flashing power light comes on every time I start the car. Just out of curiosity, should my power light still flash after the fwd fuse is inserted?