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1995 Chevrolet Silverado Z71 6.5 TD
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If you have replaced the MC and bled the brakes and with motor off you have a good firm pedal but once engine running pedal goes to the floor then I would suspect the hydro-boost to be bad.
 
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Discussion Starter · #23 ·
Update.
New Master cylinder, New hydroboost. Brakes bled. Hydroboost bled. Also drained and put New fluid in the power steering pump.
Again pump breaks with engine off they get hard. Start truck pedal goes to the floor. Drive it, sometimes if you do a few pumps the pedal gets a little stiffer but not always.
I have tried pulling the abs fuse but no change, also tried unplugging it.
The power steering pump seems to work fine. Atleast it turns my 14 wide wheels on 33s with no problem or whine.
Is it possible that the power steering pump isn't putting out enough pressure to properly build up the hydroost but turn the wheels just fine?
I am completely stumped.
 

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Discussion Starter · #24 ·
Also on the the old hydroboost after pulling I noticed that it had a slight leak
643737
 

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1995 Chevrolet Silverado Z71 6.5 TD
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It could very well be that the PSP is going bad. I believe the 96 up used the same PSP as a gasser.
Rock Auto $178 for truck with hydraulic brakes
 

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I went thru this same problem a few months ago.
One wet morning on my first brake the ABS kicked in, next stop had pedal almost to the floor.
It would stop but almost to the floor.
Replaced the 23yr. old M/C, same thing. I overhauled the H/B about 2 years ago and it was working fine.
What's left? ABS unit. Researched and found out they can fail like that. Removed it, better brakes than ever.
I do not recommend doing that for obvious reasons.
 

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1995 Chevrolet Silverado Z71 6.5 TD
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I went thru this same problem a few months ago.
One wet morning on my first brake the ABS kicked in, next stop had pedal almost to the floor.
It would stop but almost to the floor.
Replaced the 23yr. old M/C, same thing. I overhauled the H/B about 2 years ago and it was working fine.
What's left? ABS unit. Researched and found out they can fail like that. Removed it, better brakes than ever.
I do not recommend doing that for obvious reasons.
in conclusion did you buy another ABS or do you still drive around with ABS removed? Just asking.
 

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Unobtainium except used so why bother.
 
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There is an ANTILOCK light on the gauge cluster and they will set codes.
Mine did neither.
 
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That ABS unit is the one with KELSEY-HAYES on the black plastic cover? And it only controls the rear wheels correct?
 

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Thanks Glag for the info....always thought my 95 had rear wheel only ABS.
 

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Discussion Starter · #34 ·
I was out in the garage messing with the truck. Seeing what it would do and not do. Started the truck, brakes went to the floor. Pump 5 or more times they would stiffen. Turn the steering wheel left to right. After awhile I would check the pedal. Goes to the floor. Pump pedal while turning the steering wheel. Pedal stayed stiff. Hold the brake pedal and try to turn the wheel the steering wheel would get hard. When it was to the point that it didn't want to turn, I forced it. The truck died. Won't restart. Glow plug light isn't coming on. I pushed the glow plug button to heat them up but still no start. Doesn't even try, just turns over.
 

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Discussion Starter · #35 ·
I checked the fuse, its good. I'm thinking that somehow I burned up the glow plug relay. Not sure how it's possible from what I just did. Because it always starts up immediately with no issues. When its running it runs flawlessly.
 

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Check the fuses in the under hood fuse box.
 

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The glow plug fuse does not power the GPR. It protects the gauge cluster and the PCM from the glow plug signal.
It only has power when the glow plugs are glowing.
The ENG-I fuse powers the GPR and many other things.
 
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Discussion Starter · #39 ·
I didnt know that. I looked back into the fuse box. ECM-B fuse was blown. Swapped it out. Turned the key and it immediately blew again
 

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Either the OPS / Lift pump circuit or the PCM, or wiring problem, only 2 things on that circuit.
Wire is ORANGE.
 
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