M998 TIME DELAY MODULE (12338603) ISSUE?

[Iambiig]

When you step on the gas and the tdm valve engages the fan clutch, is it supposed to disengage the fan clutch after 20 seconds or so? If I get mine to kick on from mashing the gas pedal, it stays on. Truck runs at constant 187 degrees while on. Do you have to do something to "turn off" the TDM.

 

[Mogman]

The time delay module is designed to disable the fan clutch not enable it.

 

[Mogman]

Somewhere off of this site:

The function of the time delay module is to give you a 20 second of free fan blade rotation during fording operations. If you quickly floor the accelerator pedal the linkage hits a switch on the injector pump that triggers the TDM to allow the fan to rotate freely. That way when the blades strike water they stop spinning rather than shearing off.

 

[Mogman]

Time to troubleshoot the TDM/fan control

 

[Iambiig]

Somewhere off of this site:

The function of the time delay module is to give you a 20 second of free fan blade rotation during fording operations. If you quickly floor the accelerator pedal the linkage hits a switch on the injector pump that triggers the TDM to allow the fan to rotate freely. That way when the blades strike water they stop spinning rather than shearing off.

so. in this case, if I quickly accelerate, it sounds like a jet engine turns on (is this the clutch disengaging?) and stays that way. Keeping the engine at about 187 degrees. If just operating normally (no mashing the accelerator) the temp goes to about 220 and stays. Is this normal? Feels much more comfortable at 187

 

[Iambiig]

Can you test the TDM fan control with an ohm meter?

 

[Maxjeep1]

Can you test the TDM fan control with an ohm meter?

Black dog customs has a really good video on how to test it. If I remember right it should be around 75 ohms?

 

[Mogman]

Black dog customs has a really good video on how to test it. If I remember right it should be around 75 ohms?

LINK?

 

[Maxjeep1]

LINK?

 

[Mogman]

I do not mean to pick it apart because we NEED more videos like this, but the first thing is the clutch should disengage when 90 PSI of air is applied and unfortumately it does not troubleshoot the TDM at all.

 

[Maxjeep1]

I do not mean to pick it apart because we NEED more videos like this, but the first thing is the clutch should disengage when 90 PSI of air is applied and unfortumately it does not troubleshoot the TDM at all.

I thought he put the ohm meter on it? I was watching it for the temp sensor trouble shooting. I will watch it again.
After further review, he did the ohm test on the Cadillac valve…

 

[Mogman]

The first thing I would do is follow the video, if the clutch engages and disengages with the first step unplugging the two wire plug between the TDM and the Cadillac valve, if so the clutch and Cadillac valve and the (temp switch in that it is closed while cold) are all working, I suspect they are.

Then there are 4 wires going INTO the TDM, run power, ground, "kickdown" signal from the IP and one from the temperature switch.
So
Look at the schematic in the TM for the wire numbers, the kickdown wire should go to 24V when you floor the pedal, not much else left if all that is good than a bad TDM.
If you can get your hands on one of course a swap would be the easiest way.

 

[Hummer Guy]

Shouldn't the operating temperature be at 200 and the fan come on at 220?