Connecting TDM strange issues with air restriction gauge, temp and transmission

[johnhjohnson2]

I have a 1989 M998 bought at auction. When I received it the TDM was unplugged where the fan runs constantly which I have heard is common. When I connect my TDM my fan does not quit running when in neutral or drive with parking brake on. When I drive the vehicle for 20-30 minutes with TDM connected my temperature will run in the 220-240 range. If I leave it disconnected my temp hardly ever gets above 160. I am certain it isn't the gauge malfunctioning as I can feel massive amounts of heat radiating near parking brake when TDM is connected. Also, my air restriction gauge does not operate unless the TDM is connected. Does the TDM need to be connected for the Air Restriction Gauge to function normally?

Also I washed the engine off today and the plugs to TDM got wet and were not connected. The air restoration gauge started working and my transmission would not shift out of first gear. As soon as plugs dried out the air restriction gauge did not come on and truck shifted normally.

Sorry for all the random facts just hoping for some direction as where to start looking for issues. I have ordered a new TDM as I have read they fail frequently but am unsure if the problem may lay elsewhere. I am just looking for how these things could be connected.

thanks

 

[Milcommoguy]

Check the oil in the control module and be sure the vent is not plugged. If plugged a Q-tip works good. You didn't say but my guess would be you just finished painting it. Happens all the time.

 

[johnhjohnson2]

I haven’t painted it but it is full of that red clay dust from Oklahoma. You can try and wash it 100 x and it still never seems to go away. It’s so fine and cakes up so strongly that wouldn’t surprise me in the least. I’ll def check that out. Thanks!

 

[Action]

The air restriction guage has a rrubber hose that runs to the air filter can i hooks to nothing else.

 

[Dock Rocker]

The air restriction guage has a rrubber hose that runs to the air filter can i hooks to nothing else.

I agree with this. Unless something is creating an actual restriction in the intake air flow somehow.

To me this seems very strange. Systems that have nothing to do with each other are having issues as if they are somehow connected.


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[Action]

I have a 1989 M998 bought at auction. When I received it the TDM was unplugged where the fan runs constantly which I have heard is common. When I connect my TDM my fan does not quit running when in neutral or drive with parking brake on. When I drive the vehicle for 20-30 minutes with TDM connected my temperature will run in the 220-240 range. If I leave it disconnected my temp hardly ever gets above 160. I am certain it isn't the gauge malfunctioning as I can feel massive amounts of heat radiating near parking brake when TDM is connected. Also, my air restriction gauge does not operate unless the TDM is connected. Does the TDM need to be connected for the Air Restriction Gauge to function normally?

Also I washed the engine off today and the plugs to TDM got wet and were not connected. The air restoration gauge started working and my transmission would not shift out of first gear. As soon as plugs dried out the air restriction gauge did not come on and truck shifted normally.

Sorry for all the random facts just hoping for some direction as where to start looking for issues. I have ordered a new TDM as I have read they fail frequently but am unsure if the problem may lay elsewhere. I am just looking for how these things could be connected.

thanks

The air RESTRICTION guage doesnt "come on". It doesnt move unless the air filter is clogging up. After cleaning, push the small tab at bottom of guage to lower the indicator. You can remove hose from air filter can and suck on it to verify it works properly.

 

[johnhjohnson2]

The air RESTRICTION guage doesnt "come on". It doesnt move unless the air filter is clogging up. After cleaning, push the small tab at bottom of guage to lower the indicator. You can remove hose from air filter can and suck on it to verify it works properly.

The gauge works fine but there is no vacuum on the line to make it work unless the two plugs from TDM are hooked up. When I plug them up you can hear the air at the gauge and if I restrict air flow it shows on gauge appropriately. When i unplug the two plugs of TDM the gauge does not function.

 

[Action]

The gauge works fine but there is no vacuum on the line to make it work unless the two plugs from TDM are hooked up. When I plug them up you can hear the air at the gauge and if I restrict air flow it shows on gauge appropriately. When i unplug the two plugs of TDM the gauge does not function.

What do you mean by if you restrict airflow? You can block the air intake at any time and make the gauge work. If those 2 systems on your HMMWV are hooked up to each other, I would take it back.

Ideally, the gauge will never move. It's only purpose is to inform the driver that the air filter is dirty.

 

[Milcommoguy]

Someone has their wires and hoses crossed ??? But again, nothing is impossible in a Hummwv. Saw that on a tee shirt, guess it's true.

 

[Retiredwarhorses]

The most confusing post of the week award....lol

 

[johnhjohnson2]

Hey at least I won something lol. I have been all through the field manual, wiring diagram etc. I can't figure it out. Had my guy at local off-road shop check it out too. I have done everything I know to do with my limited knowledge to try and narrow it down, I put in the recommended additional ground wire harness, cleared vent lines w/ air etc. No change

The most confusing post of the week award....lol

 

[Milcommoguy]

Restricted tail pipe outlet? Check for a banana.

 

[Action]

I have a 1989 M998 bought at auction. When I received it the TDM was unplugged where the fan runs constantly which I have heard is common. When I connect my TDM my fan does not quit running when in neutral or drive with parking brake on. When I drive the vehicle for 20-30 minutes with TDM connected my temperature will run in the 220-240 range. If I leave it disconnected my temp hardly ever gets above 160. I am certain it isn't the gauge malfunctioning as I can feel massive amounts of heat radiating near parking brake when TDM is connected. Also, my air restriction gauge does not operate unless the TDM is connected. Does the TDM need to be connected for the Air Restriction Gauge to function normally?

Also I washed the engine off today and the plugs to TDM got wet and were not connected. The air restoration gauge started working and my transmission would not shift out of first gear. As soon as plugs dried out the air restriction gauge did not come on and truck shifted normally.

Sorry for all the random facts just hoping for some direction as where to start looking for issues. I have ordered a new TDM as I have read they fail frequently but am unsure if the problem may lay elsewhere. I am just looking for how these things could be connected.

thanks

Those statements don't agree with each other...
If there is no change in the fan with the TDM plugged or unplugged, why would the temp be any different in both situations?
Also, just because the fan is spinning, doesn't mean it is locked to the engine. It free spins by itself with the engine running.