View Full Version : Replacing the TCM

02-18-09, 02:42 PM
I need to replace the TCM on a 1999 Cat (VN ..XR012482). I've removed the panel under the glove box and exposed the air vent. The instructions I have indicate I should "rotate the air duct up and out of the way. However, I cannot seem to figure out how to move it. I can see the TCM but can't get the duct out of the way. Any suggestions?

02-18-09, 05:45 PM
I was just in my dash last week - had to replace a heater core. I know where everything is now. No it was not fun. I have a few suggestions if someone else ever has to get their heater core out - the GM service manual leaves out removing one brace that is necessary for damage-free removal of the dash (not anything a little JB-weld can't fix :)

I think it may be easier to remove the passenger side AC air vent on the dash (turn the vent full up or down, then pull it out of the housing); then that entire plastic assembly comes out with four screws; it exposes the TCM behind it and you may not have to sit with your head in the floorboard to see it and remove the connector on top of it.

If you ain't dizzy like me and wish to stay on the floor, the air duct (tube running the length under the glovebox for passenger floor heat) is held on by a black plastic push-tab at the end of the duct near the door. The push-tab has a pin in the center that locks it into the hole. Push the pin out of the center of the plastic retainer (don't lose it) and then pull the fitting loose from the tab at the bottom of the dash. The other end just pushes onto the assembly under center console. That's all that holds it. Take the pin and plastic clip out and it shoud rotate.

02-19-09, 02:00 PM
Thanks for the feedback. However, I already took out the passenger side A/C vent. Didn't see the TCM below but honestly can't say I was looking for it as I had the brilliant idea of removing the glove box to expose it. Looked easy in the factory manual I have, but the air bag panel wouldn't pivot up as expected so couldn't get the box out.
I will take the vent apart again and see what I can see.

Also, I did remove the pin in the duct but could not get it to budge on the driver end. You say it should just pivot up (or down)?

Your other point was interesting, replacing the heater core. When the engine heats up I get a smell of anti freeze in the passenger compartment, but can not find any leaks in the engine compartment. I am suspecting a small leak in the heater core, but not sure how to best check that. Any hints?

02-19-09, 02:20 PM
The panel that covers the air bag is held by a long hinge screw. If you already have the pass. side air vent and the plastic housing removed, you will have to get a torx head with extension and remove the screw, pull it out, then the panel lifts away.

I had removed mine since I was taking it apart so I can't really say if it does pivot but it should pull loose easy enough since it just slides over the tube on the heater unit.

I found heater core leak 2 years ago by observing a small plastic tube above the tranny dripping coolant. This tube drains directly from the heater core box. Not much other way to see it without tearing out the dash. I imagine most 97 may have possibility of crack in the plastic housing for the inlet and outlet tubes; the new core had a more substantial plastic housing for the end of the core. I bought the new core, but since it was losing about 1 cup every two weeks I ignored it. When it started flooding my floorboard a month ago it was time to fix it.

02-28-09, 02:08 PM
TCM as in traction control module?

03-01-09, 01:38 PM
TCM - Transmission Control Module. They put it in the tags at the bottom of the page.

98 Catera
03-01-09, 03:21 PM
OHHHH, thats cool, I never noticed that.