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8.1L/496 Tech

Learned from watching south main auto repair on youtube, disconnect both ends of the harness, put 12v and ground on one end, and the bulb on the other. If its dim, the wiring is bad. Just make sure the sensor and abs module are disconnected. Using a headlight bulb as a load instead of a test light allows more current to flow, so if theres any resistance in the wires the bulb will be dim, just dont beat up the terminals in the connectors
 
oh yeah, I've seen him do that. Smart.

I'll try to give it a shot. Thanks for the idea.
 
BDK said:
Swapped out the oxygen sensors. Cleared the codes. Let it idle for 30 minutes, took it for a drive. Runs great. It had Denso sensors in it, unknown if they are OEM. I'm impressed with that motor. In limp mode, 4500RPM up a 8 mile grade with the AC on and it never got over 210*. 18,000lb RV with a 3500+lb toad.
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Next time...look at the CTS data on your scanner instead of the temp gauge. I was suspicious towing across the desert one day and plugged in, CT on the scanner was 247, intake air temp 142, temp gauge on the dash said 195.
 
Jmmorriso said:
Learned from watching south main auto repair on youtube, disconnect both ends of the harness, put 12v and ground on one end, and the bulb on the other. If its dim, the wiring is bad. Just make sure the sensor and abs module are disconnected. Using a headlight bulb as a load instead of a test light allows more current to flow, so if theres any resistance in the wires the bulb will be dim, just dont beat up the terminals in the connectors
Click to expand...

Still haven't done that.
Crap ton of other shit to do.

Put 1000ish mi on the truck since I swapped the MC. Brakes haven't locked back up since. I think that issue is fixed.





One thing to note about the ABS problem is that if I hit a pothole or a hard bump, the ABS light will blink.
I'm thinking there has to be a bad connection.
 
Bebop said:
Still haven't done that.
Crap ton of other shit to do.

Put 1000ish mi on the truck since I swapped the MC. Brakes haven't locked back up since. I think that issue is fixed.





One thing to note about the ABS problem is that if I hit a pothole or a hard bump, the ABS light will blink.
I'm thinking there has to be a bad connection.
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The amber ABS light or the red brake light or both?

These have an issue with vibrations from the solenoids cracking some solder connections for the main power relays in the EBCM...I usually remove the EBCM from the ABS unit, remove the torx screws and use a razor blade to slice through the sealant to pull the lid off, then look it over with a magnifyling glass....I usually find 3 or 4 connections that look a bit "foggy" and reflow them, then everything works as it should again.

There is also a ground on the frame toward the front of the drivers door that is shitty....clean everything up and use a bolt and nut instead of the self tapper that GM used that was probably stripped during assembly at the factory.
 
Amber light.

What you're saying is very interesting.

I'll look into all of that.

Thank you !
 
Bebop said:
Amber light.

What you're saying is very interesting.

I'll look into all of that.

Thank you !
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Usually the scenario I described brings on the red light AND the amber light...

Find a scan tool that can pull ABS codes. That's your starting point
 
Lbhsbz said:
Usually the scenario I described brings on the red light AND the amber light...

Find a scan tool that can pull ABS codes. That's your starting point
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Oh...

Never seen the red light. Ever.

Scan tool shows missing communication with pass sensor and that's it. See a few posts above.
 
Been driving it around quite a bit this month.

Brakes have never locked up again. Soooo I'm gonna say that the master cylinder was the original issue.

ABS light still flickers from time to time, haven't had time to dig in.
 
Drove 450 miles on flat highway, thought the gas gauge was broke. Got 13 MPG hauling ass at 80.

Empty 2wd CCLB. Full tuneup, cleaned the throttle body (probably the first time ever since ‘02), new K&N cone filter, cleaned MAF grid (also first time ever).

She’s peppy as hell now.
 
Lbhsbz said:
The amber ABS light or the red brake light or both?

These have an issue with vibrations from the solenoids cracking some solder connections for the main power relays in the EBCM...I usually remove the EBCM from the ABS unit, remove the torx screws and use a razor blade to slice through the sealant to pull the lid off, then look it over with a magnifyling glass....I usually find 3 or 4 connections that look a bit "foggy" and reflow them, then everything works as it should again.

There is also a ground on the frame toward the front of the drivers door that is shitty....clean everything up and use a bolt and nut instead of the self tapper that GM used that was probably stripped during assembly at the factory.
Click to expand...
I've actually had the bad ground on the frame in that spot before. Also if one of your wheel bearings are on the way out I've seen them set ABS codes for air gap.
 
shortbus4x4 said:
Also if one of your wheel bearings are on the way out I've seen them set ABS codes for air gap.
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I've actually seen this before. 2wd 2500, neighbors truck. "Oh well, I ain't need no annie locks anyways..." A month or two later the wheel folded up into the fenderwell backing out of the driveway.
 
45acp said:
I've actually seen this before. 2wd 2500, neighbors truck. "Oh well, I ain't need no annie locks anyways..." A month or two later the wheel folded up into the fenderwell backing out of the driveway.
Click to expand...

Same here, have saw that a few times. Last one was an ol boy at work. He mentioned the light popped on. We jacked it up in the air and both wheels were just flopping around!:shaking:
 
Bebop how's the abs issue?

Buddy of mine described same issue as what we have and he re-solder parts of the abs module. I'll have mine done hopefully this month. I'll take pics of process so it should help out for everyone since it'll be free and takes bit of time
 
A couple months ago, as I was driving it, the front right wheel locked up at 70mph while on the highway. I almost crashed bad.

After I took it apart, the pad had worked itself sideways, like the caliper was only using one of the 2 pistons, then the pad fell out of the groove and wedged itself between the mount and the rotor, thus locking it.
When I swapped the previous caliper, it was kinda doing the same thing too.
This car was crashed on the front right and I'm kinda wondering if the upright is tweaked and the caliper is not centered. It's weird.

I slapped a new caliper and pad and it drives around but I don't trust the vehicle anymore.



I don't have any of the signs of a bad ABS module (like the code C0265 "EBCM Relay Circuit Low"). The only ABS code happens when the front right wheel speed suddenly drops like I posted above. It does it every so often. I tried a new wheel bearing, new ABS sensor, nothing. I don't think it's a sensor distance thing (VR sensor too far from the teeth) because the speed randomly drops out when you're at 4mph, the same way it does it when you're on the highway at 70mph. Might be a wiring thing but I can't figure out where.

I also have a lot of other shit to do in life and since I haven't needed to tow anything so it just sits.
 
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