Dash removal and replacement

[Navyguy92]

Does a 98' dash swap straight across to an 88'? I'm not sure if the mounting bolt/screw holes line up for the dash mounts. I know the rest of the interior parts swap out with no problem, but not so sure about the dash.

 

[someotherguy]

Does a 98' dash swap straight across to an 88'? I'm not sure if the mounting bolt/screw holes line up for the dash mounts. I know the rest of the interior parts swap out with no problem, but not so sure about the dash.

It depends on what your definition of "with no problem" means. There's lots of problems along the way, for that entire swap, but many have done it and it has been written up in great detail all across the interwebs.. including probably several posts on this site.

To be quite literal though, yes, the later style GMT400 dash "bolts up" in an older GMT400 cab, it uses the same bolt locations and swivel studs down low in the kick panel area, and the same screw locations across the defrost vents.

You'll want to change the steering column support for it to fit correctly.

You must be registered for see images attach

You must be registered for see images attach

Don't forget to add the passenger A-pillar grab handle bracket. You wouldn't wanna leave those two gaping holes in the plastic trim, would ya?

You must be registered for see images attach

You must be registered for see images attach

Richard

 

[dfarr67]

Have a 89 K1500 which I have the interior out for sound matting, along the way decided to clean out the evaporator of pine needles/crap and rebuild the ac as it hasn't worked in years. Getting the lower hvac shrouds out was bad enough and trying to sneak it back in is impossible (very few jobs kick my ass), can I loosen the box mounts through the firewall so I can get about 1/2 inch between the firewall. If I have to pull the dash I will but would like to avoid.

 

[Das Hatt]

Have a 89 K1500 which I have the interior out for sound matting, along the way decided to clean out the evaporator of pine needles/crap and rebuild the ac as it hasn't worked in years. Getting the lower hvac shrouds out was bad enough and trying to sneak it back in is impossible (very few jobs kick my ass), can I loosen the box mounts through the firewall so I can get about 1/2 inch between the firewall. If I have to pull the dash I will but would like to avoid.

I just went through this. I was going to replace the dash anyway so I took the dash out, but I could not get the lower plastic pieces back on without pulling out the entire HVAC box and essentially reassembling it. I wish you better luck than I had.

 

[dfarr67]

I just went through this. I was going to replace the dash anyway so I took the dash out, but I could not get the lower plastic pieces back on without pulling out the entire HVAC box and essentially reassembling it. I wish you better luck than I had.

I have a servo motor that has been growly since I bought the truck- the dash is in great shape. Be a shame to have to pull for this. When you pulled the hvac box- most of the bolts were on the engine side and one in cab? Any part numbers for the motors in this thread?

xc_hide_links_from_guests_guests_error_hide_media

xc_hide_links_from_guests_guests_error_hide_media

 

[Das Hatt]

I have a servo motor that has been growly since I bought the truck- the dash is in great shape. Be a shame to have to pull for this. When you pulled the hvac box- most of the bolts were on the engine side and one in cab? Any part numbers for the motors in this thread?

There is one bolt in the cab, correct. Then there is one nut in the engine bay that holds the lower part of the AC receiver/dryer bracket in place, three screws behind the coolant overflow tank, one screw where the firewall bends rearward behind a thick wire loom, and one screw directly behind the distributor

 

[east302]

I’m not sure if the TBI has it this way, but on my 98 the evaporator core line has a small hold down clip holding it to the box.

If it’s still attached to the accumulator, it may limit how much the box will move when the screws are removed at the firewall. In theory the clip might slide along the pipe, but that evaporator may hold everything back. Loosening the accumulator bracket may help. The heater core hoses would also need to pull into the cab a little. It’s something to keep in mind, but it might be enough to give you clearance you need.

You must be registered for see images attach

 

[jd33173]

I replaced the dash in my 1998 K1500 and thought I'd post a how-to. The steps below are from alldatadiy.com which, I think, mimics the factory service manual. I've added pictures to relevant parts as some of the steps are a little vague.

I'd really recommend getting a box of ziploc bags and putting the screws from each step in them. I labeled disconnected wiring with green masking tape, which makes it easier during re-installation so that you can easily spot any unconnected wiring harnesses.

Before disconnecting the battery, make sure you lower and slide the driver seat all the way down and back. That's the one thing that I really wished that I had done first.

Also, chock your tires as the shift linkage is removed when the steering column is removed.


Here are the alldata directions:

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

The numbered steps below are from the alldata directions. My comments are in italics.

1. Disconnect the negative battery cable(s).

2. Disable the SIR system:

• a. Turn the steering wheel so that the vehicle's wheels are pointing straight ahead.
• b. Turn the ignition switch to the LOCK position.
• c. Remove the key from the ignition switch.
• d. Remove the AIR BAG Fuse from the IP fuse block.
• e. Remove the Connector Position Assurance (CPA) from the driver yellow 2-way connector located at the base of the steering column
• f. Disconnect the driver yellow 2-way connector located at the base of the steering column.
• g. Remove the Connector Position Assurance (CPA) from the passenger yellow 2-way connector located near the base of the steering column
• h. Disconnect the passenger yellow 2-way connector located near the base of the steering column.

I didn't take a picture, but the airbag harnesses are near the steering column and pretty easy to spot. They're the yellow ones in the picture below:

You must be registered for see images attach

3. Remove the three relay center bolts from the underside of the wheel opening.

The Relay Center is on the driver side fender and held in place by three bolts going through the wheel well. You aren't removing the Relay Center...just unbolting it so that you can move it out of the way. If you can remove it, that might make things a little easier.

You must be registered for see images attach

4. Remove the bulkhead connector.

The white (top) part stays and is attached under the dash to the Convenience Center. There are two screws on the firewall that need to be removed. I've already removed one screw in the picture below. It's to the upper right of the white harness. The second one is diagonal to it and a little harder to reach. Remove both of those screws to allow the white harness to be pulled into the cab.

The black (lower) harness is attached with a torx bit to the Convenience Center. The red arrow points to where the screw head is. I used a T25 screwdriver, but don't know if a socket bit would have fit or not. Remove the torx screw and pry the black harness off.

You must be registered for see images attach

5. Remove the following components from the bulkhead connector:

What you're doing here is removing the harnesses that connect the white bulkhead connector to engine compartment components. The airbag and headlamp connectors are on the fender wall and easy to spot. The others are on the firewall kind of below the brake booster so they’re a little harder to reach. The wiring harness to both the wiper motor and cruise control on the firewall will need to be removed.

• a. The screws from the convenience center to the cowl
• b. The cruise control harness (if equipped)
• c. The forward lamp harness
• d. The SIR system harness
• e. The relay center

6. Remove the coolant reservoir.


Two bolts on the firewall.


7. Disconnect the antenna lead-in and the grommet.

Separate the antenna cable where it goes up to the antenna mast on the firewall.

You must be registered for see images attach

8. Remove the knee bolster.

There were three or four screws along the bottom. The top part clips on. You'll also remove the parking brake release handle (press in the two tabs and pull) and the brake cable that attaches to it. On that, twist and remove.

You must be registered for see images attach

9. Remove the steering shaft pinch bolt.

I wasn't sure which bolt they were referring to, so I removed the one in the cab.

You must be registered for see images attach

10. Remove the left and the right sill plate front screw.

11. Remove the left and the right hinge pillar trim panels.

These are just the door sill plates and the triangle piece that surrounds the hood release.

You must be registered for see images attach

You must be registered for see images attach

12. Remove the brake release handle from the cable.


See step 8

13. Remove the reaction plate assembly.


This is the outer black piece. Four bolts.

You must be registered for see images attach

14. Remove the tie bar.


There are four bolts holding the tube in place.

You must be registered for see images attach

15. Remove the knee deflector bracket. Two screws. Tap it on the bottom and it’ll pop up and off.

You must be registered for see images attach

Amen on the ziplocks, did that and wrote on the bags very useful

 

[dfarr67]

I’m not sure if the TBI has it this way, but on my 98 the evaporator core line has a small hold down clip holding it to the box.

If it’s still attached to the accumulator, it may limit how much the box will move when the screws are removed at the firewall. In theory the clip might slide along the pipe, but that evaporator may hold everything back. Loosening the accumulator bracket may help. The heater core hoses would also need to pull into the cab a little. It’s something to keep in mind, but it might be enough to give you clearance you need.

You must be registered for see images attach

System is/was blown completely apart and the old R12 compatible oil was flushed out of the evaporator, new accumulator/dryer installed too. Yes I saw that clip. I'm almost resigned on the dash but will give it another shot.