GMT400 Suburban - poor life choices MkII

So who owes me $1.50, because both of my long distance diagnoses via text were right 

glad it wasn’t full on rebuild time, those guys sound reasonable.

In reply to Patrick :

Damn right I owe you, that's why I messaged you first!

I finally had time to take a look at the ABS setup on the truck. 

From what I can tell this is the Kelsey-Hayes 3-channel system, and it's showing the following codes:

• 61 - right front reset switch open circuit

• 66 - pump motor relay short

• 86 - ABS indicator lamp shorted

The last one is odd, as the ABS lamp works fine. The second one is most concerning though, since I've not been able to find a replacement module or rebuilder. 

Im not concerned about retaining the ABS, so I could swap the MC and re-plumb around the EHCU, but that will defeat my TC lockup clutch circuitry. 

I think for now I'll leave the ABS alone, wire a toggle switch directly to the trans harness for the clutch, and continue to live without cruise control. 

Spent a little time on the truck, but no pics(yet). I swapped out the blower motor, it's nice not having the fingernails-on-a-chalkboard anymore. 

Next I started wiring up a circuit to manually lock up the TC clutch  since my failed(and apparently NLA) ABS module is preventing any voltage from getting to the TC lockup circuit, I wired a fuse from the battery to a switch in the dash, then routed the wire under the truck. I need to crawl underneath tomorrow, T off it to the 2nd wire on the trans, then manually ground the circuit since it also has a switched ground. Schematic for reference, though I don't have 12v from the brake pedal switch due to the ABS problems.

I also swapped out the rear brake shoes. I was surprised to find I have the larger size drums, I'm not sure if that's part of the 3-channel ABS system, or just an upgrade option, but I'm happy to have them! Unfortunately it's a real pita to change them by yourself as there are multiple springs and pieces that need held together as you install them. Fortunately a friend stopped by & was able to help. Now let's hope the self-adjusters work, as there's no plug on the backing plates for adjuster access...

Grease the adjusters on the rear drums, find a steep hill, back down at 25 MPH and then hit the brakes hard, right on the edge of lockup until you come to a stop.  Repeat 3 times and your rear brakes will be as good as they're going to get.

I walked out this morning to find a puddle under the LR wheel, pulled it apart & it looks like it was leaking from the front of the wheel cylinder. Pushed the plunger in w/a screwdriver, cleaned it up and adjusted both sides, then put the drums back on & checked the brakes. They seemed to be holding pressure & after some adjustment on both sides I had decent pedal feel. 

I finished wiring up the TC clutch manual lockup switch, then took it for a drive. At the stop sign down the street the brake pedal dropped again. Crap. I need to check if the leak returned. I tried the lockup clutch while I was out, but it didn't seem to work either. Damn do I hate working on vehicles...

Well I checked the brake fluid & it's still full. I'm guessing I either have air in the lines, or need to readjust the drums. 

At this point if I end up needing to re-bleed the brakes, I'm just going to bypass the NLA ABS module so I know there's no chance of air remaining in the system. 

I finally made a bit of progress on the truck today. First of all - how have I lived my whole life without one of these?

The GM adaptor is a bit jankey, but seemed to work well after I finally got it sealed. 

And finally the brakes actually work well again!

Next I replaced the headlight switch because the cluster lights were intermittently inop, and I was pretty sure I lost the taillights too when that happened. 

Then I got setup to tow. 

I installed the P2 in the ashtray, since there’s no good place under the dash for it & I won’t be using the ash tray anyway. 

I still don’t have any torque converter lockup & im not sure why. I’m tempted to take it back up to the mechanic in IL and let him figure out a redneck fix to work around the dead/NLA ABS module. 

No major updates on the truck, but I did tow a 6’x12’ U-Haul trailer 840mi up to IL last Friday, cram it 100% full of crap floor-to-ceiling, wall-to-wall, and front-to-back, then tow it 840mi back home on Tuesday. 

The good news is the truck made it there & back with out breaking down. On the way up it was cool & rainy so I was able to keep steady between 70-75 empty, but it was hotter on the way home & the temp gauge started climbing if I went above 70...or turned on the a/c, sadly. That was somewhat ok though, as having the windows down helped drown out the drone of the ever-growing hole in the muffler & evacuated the exhaust fumes. 

I averaged 9.6mpg loaded, which is better than I expected. However the day after I got home the driver side seatbelt decided to no longer latch.

At this point I definitely need a muffler & shocks. Then I need to replace the windshield so it’ll stop leaking into the dash. I have a pair of seatbelts on order too. 

I’ve never been able to get the TC to lockup either, so I’m starting to think the lockup clutch may be bad. I need to find a local trans shop & see if they can figure it out and/or rig it up to work somehow without the ECU’s involvement. I might just have them go through the trans too & see if there’s anything that could be done to help make it more durable for towing. 

It really doesn't seem like it should be heating up like that.  What do you suppose that is about?  I suppose a non-locking torque converter could put out some extra heat, but I would think if your cooling system was in good shape, it should be able to handle that.  Maybe you've already mentioned a potential cause and I'm just not remembering.]

At any rate...glad it's working as a tow vehicle for you!  Steady improvements are fun!

In reply to ClemSparks :

My understanding is not having lockup really generates heat, based on what I’ve been told. 

I haven’t been driving the Suburban much this summer, but I took it to Aeromoto’s shop a couple weekends ago so he could lend a pair of hands to help me wrestle a new slave cylinder on the RR brakes. 

I went out to start it tonight for the first time since then. It started up fine like always, but died a couple seconds later. I tried again, but it took several seconds of cranking before it fired, and it was running quite rough. It smoothed out a bit after revving it, but I needed to get to the store & didn’t want to risk getting stranded, so I E36 M3 it off & took the Miata instead. 

So it looks like I have a project for this weekend...