C1500 Suburban Master Cylinder questions

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redfishsc

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So yesterday my wife got stranded because the 99 Suburban C1500 broke down. Symptoms are a sudden ABS light on the dash (ABS functioned properly with no light prior to this).

Also, the truck wouldn't accelerate. Engine RPM increased but very sluggish acceleration.

Truck only just now arrived at the house via tow truck so I haven't investigate anything yet. Sounds to me like a bad rubber brake hose, bad master cylinder, or stuck caliper.

I'm not sure that any of those other than mayb the MC would set off the ABS light.

Either way I'm tempted to swap the old MC just as preventative. I know the old myth about using the GMT800 MC has been debunked. I've seen suggestions on using the C2500 Master Cylinder on a 1500. Is that a legitimate improvement?

Are there any good options that don't have that terrible clip-on lid? Not interested in anything that might risk brake reliability but damn I hate that lid and cup design

Lastly, regardless of the model MC, what brand other than OEM is recommended for reliability? The one on it now is probably a cheap parts store junker.
 
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HotWheelsBurban

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Wagner, Bendix, Eis and Raybestos used to be good brands. I would stick with a name brand rather than the store brand....
 

redfishsc

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Well we got it home, it's driving with no other symptoms. So whatever it is it's intermittent.

Pedal is firm. Firmer than most gmt400 vehicles honestly
 

Schurkey

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1. I wouldn't expect a master cylinder to trigger an ABS light. You need a scan tool to find out what the computer has to say about the problem. Most ABS lights I've dicked with have had a failed wheel sensor harness as the root cause. Sometimes the harness can be repaired, sometimes I've replaced the sensor, and sometimes the whole wheel hub and sensor assembly is trashed.

2. I'm not saying it cannot be something other than a wheel sensor, just that that's most-likely. The scan tool should help with diagnosis.

3. Get a master cylinder intended for the brake system you have. Likely JB5, maybe JB6. Substitute JD if you've got hydroboost. Far as I know, JB/JD5 and JB/JD6 take the same master cylinder--1 1/8 (29mm?) main bore, 40mm Quick Take-Up bore. The retailer can help you select the proper one for your brake system.

4. Calipers are suspect. Inspect...everything.

5. Flush all the old fluid. Use a scan tool to flush the ABS unit.
 

someotherguy

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Without more info/troubleshooting, sounds like the hose. If you go drive it for a while it'll likely come back. Then you can jack up the front and see if either tire will spin easily. When my '92 had a hose going bad (first time I'd personally dealt with that issue so it was new to me then) it would pull at first, then just locked up out of the blue, when I had towed it to the alignment shop after the front end rebuild. Couldn't pull it onto the rack. Later the pressure will bleed off and it will seem "normal" for a short while.

Richard
 

redfishsc

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I've put about 50 miles on it so far since having it towed home and no malfunction.

Today I'm putting it on Jacks and looking around. I'll check especially for damaged wheel sensor.
 
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