1992-2002 Kelsey Hayes ABS Scan Tool Power Bleed

[hatzie]

This will fix the GMT400 spongy brake pedal problem after the ABS ingests air from a broken brake line or the ABS gets angry with you but isn't dead. You should do this when you change the brake fluid every 24 months or so.

I do a pressure pot bleed til all four wheels run clean, power bleed the ABS motor, and pressure bleed the system again at all four wheels to rinse the crud out that the power bleed just broke loose.

First off... This is ONLY for the later 4wheel ABS systems.
My recommendation on the early GMT400 88-92 RWAL trucks is to remove the ABS motors, hook the rear brake line directly to the combination valve, and do a 4 wheel bleed. This is the ABS with the long narrow box mounted to the side of the Combination valve under and toward the LH fender from the Master Cylinder. Some 92 had RWAL and some had the Kelsey Hayes 4WAL.
https://www.gmt400.com/threads/1990-...removal.11427/

If the above article goes away I have a copy ferreted away.

I have done this on two GMT400 trucks... 1995 K1500 & 2000 GMC C2500 Sierra. I've also done this on a couple off topic GM vehicles as well... 2005 Silverado 2500HD & 2009 Impala SS.
It fixes the spongy brake pedal.

Tools...
Motive type pressure bleeder and master cylinder adapter. Mine is a weed sprayer and home brew master cylinder cap for the square reserviour and a used GM J-35589 adapter for the round camlok cap reserviours.

1992-1994 12 terminal ALDL... I haven't done this on a 1992-1994 GMT400 truck... However... It should be possible on 1992-1994 with a Tech 1, Tech 1A, Mastertech MTS3100, or Tech 2.
The Tech 1 type tools (Tech 1, Tech 1A, and Mastertech MTS3100) all use the same program cartridges.
You'll need the Mass Storage cartridge with full 81-94 GM coverage or the ABS cartridge that supports your truck...
The Snap ON MT2500 may be able to do the 92-2002 trucks with the right cartridges, personality key, and adapters.
You may also be able to do this on the 1992-1994 trucks by shorting terminals on the 12 terminal ALDL jack in a specific pattern. See F1 in this article. https://www.motor.com/magazine-summa...wal-june-1998/
If the article disappears I've saved the text.

(1995 ONLY) 16 terminal J1962 ALDL/OBD I is possible with the same tools but you need the J1962 OBD II cable interface box and J1962 OBD I cable for the Tech 1, Tech 1A, or Mastertech MTS3100. The Tech2 will handle a 1995 with no problems at all. I haven't tried an MDI on a 1995 OBD I vehicle but you're welcome to try it... It might not work because the J1962 OBD I port is actually speaking 8162 baud ALDL on terminal #8 (Proprietary GM ALDL/OBD I) and not OBD II. Just to make things a bit more confusing... ALDL is not OBD I but 1995 ALDL was also OBD I in some cases.

For 1996 to 2013 rigs that are OBD II compliant you need a Tech 2 or an MDI or VX Diag and Tech2Win on a laptop. There are several OBD II tools that will do this as well such as the Snap ON MT2500.

A picture is worth 1,000 words so how many is a video worth???

Power Bleeding ABS on 1998 GM CK Light Truck With...

According to the MOTOR article you can set the tire size in the ABS controller using a Vetronix Scan tool (Tech 1, Tech1A, Tech 2, Mastertech MTS3100). If that's true it really is a necessary step to perform when you change from the stock tire diameter.
Updating the tire size in the ABS controller made a larger difference in perceived braking performance then I originally thought possible... on my 2005 Silverado when I changed from the stock 30.5" 245/75R16 tires to 31.6" 265/70R17 tires... Yes the ABS and PCM tire calibrations are separate on my 2005. The Vetronix tools can't easily modify the PCM revs/mile calibration either I had to go aftermarket for that little dance.

[EVRLET]

Great info!!!

But spending $300+ on a scanner just to bleed the brakes and it sits in my toolbox collecting dust...no bueno.

Unless there are other uses for a tech 2 to justify the purchase?

[hatzie]

If you're working on a 96 or later I wouldn't recommend a Tech 2. I'd only buy one if you have one of the earlier rigs because it still supports up to 2013 GM vehicles.
If you have a 1996 or later truck you can get a $125 VXDiagGM or a $200 MDI clone and a $100 refurbished laptop that will support up to 2013 with Tech2Win and at least 2018 with GDS.

The Tech 2 and MDI do a whole lot more than just bleed the ABS. They're one of the least expensive bi-directional scan tools for your GM. They talk to every controller in your GM vehicle. They will command various controls on and off and to various states for troubleshooting and they're also a GM SAE J2534 passthrough service programming tool for flashing your ECM/PCM/BCM/HVAC/SIR/ABS/RADIO-matching/KEY-programming/Matching-Remotes etc. If you're working on a 6.5L diesel it's the only scan tool that's worth bothering with.

Labor is around $100/hour or more depending on who you take things to.

Mine has paid for itself many times over. I recently used my Tech2 to troubleshoot the evap system on my 2005 Silverado and re-program the angry PCM on my 2009 Impala.

What I saved on one of those operations more than paid for the tool to sit on a shelf and collect dust for a while. Not to mention my lack of confidence in the competence of dealership and other techs...

Changing the battery made the PCM angry in my Impala. It set a P0606... Towing to the dealer and re-programming my Impala would've been over $400... $300 tow and at least $150 for programming the PCM... if they even tried to reprogram it and didn't just slap a new $300+ PCM into my car and charge me for programming the new PCM $300 tow + $300 PCM + $150 Programming.
I've done a TDC Offset Relearn on my 6.5L diesel in my GMC. That's not a super cheap operation at the dealer.
Even the diagnostic time for an ABS bleed will cost you around $100...

If you're doing an LS swap you will need one of these tools. Your local dealer will be far too costly to handle the PCM work.
HP Tuners etc will handle some PCM work and diagnostics on the LS vehicles, but not all, and it also will not talk to the 6.5L diesel.
Tools like HP Tuners will not talk to any vehicle systems other than the PCM/ECM/TCM they support. This leaves out ABS & SIR systems among others.
Decent mechanics usually have several scan tools for various jobs because there's not "One tool" that does all jobs well. It's the price of admission... I have eleven scan tools that I've collected over the last thirty five years in this game and I'm not a professional mechanic.

Here's a post I made in another thread outlining service programming with these tools.
http://67-72chevytrucks.com/vboard/s...3&postcount=44

[EVRLET]

So you’re saying since I have 1996+ Chevy trucks and I’m going to start dabbling with HP Tuners, that you recommend a VX or MDI clone to add to the arsenal? If I read it right, you’re also saying that in addition to the VX/MDI, I’ll need a laptop with Tech2win as well? Does that mean the scanner is one platform and the laptop another platform and together I’ll be able to conquer the electronics?

[hatzie]

If you're committing to using HP Tuners then you're buying a laptop. VX Diag or an MDI clone are $125-$225 and they will do 96-2019 or so on the same laptop.
I'd lean toward spending the extra Benjamin on the WiFi MDI because it's a full clone of the GM tool so it's likely to keep working with AC Delco TDS the longest. But it's your bucks.

[EVRLET]

Copy. Great info again. Now to get back into the electronic mindset from my military days...where’s my TO

[hatzie]

Originally Posted by EVRLET

Copy. Great info again. Now to get back into the electronic mindset from my military days...where’s my TO

Glad to help.

If you can find the GMT400 LSSB?? (CUCV II) TMs I bet they are at least somewhat relevant to the Civilian rigs. Check on Steel Soldiers in the TM section.

The thread with the scanned 1988-1998 GM service manuals from my library are in my signature. They'll get you started til you can lay your hands on paper copies.

[hatzie]

You don't have to go with Asian no-name laptops.
You can find some nice hardware that's not on the bleeding edge anymore but it's plenty serviceable with lots of life left in it for this task.
Here's a refurbished HP ProBook 6470B metal case laptop running Windows 10 PRO 64bit for $144.19
https://www.newegg.com/Product/Produ...82E16834265232

I'm using an HP 8560W I bought in 2010 for work. Not really looking forward to upgrading.