1995 Sonoma ABS brake problems

I have a reg cab 4x4, 5 spd, 90K miles. Every now & then when I stepped on the brakes I heard a sound like a goose honking. I also hear a whooshing sound. So Finally my brake pedal got weak and the ABS & Brake light came on. The fluid reservoir was full. I inspected my brake lines (pretty rusty) and saw a weeping area where my rear lines were connecting to the wheel cylinders. I replaced both lines and changed the master cylinder. I primed the master prior to install then bled the lines in the proper order. (Not my first rodeo). So I then changed the vacuum brake booster without having to disconnect the master cyl from the brake lines.

When the truck is not running, the brake pedal is pretty firm. When I start the truck and test drive the brakes go down low, I hear the whooshing when I step on the brakes and the abs light is on. I tried pumping the brakes when coming to a stop, heard the “goose honk”, the abs light went out for 2 seconds and came back on. Now, with the truck running, the whooshing sound happens every time I press the brake pedal. The vacuum booster was a reman from a local autoparts store. Could it be the unit was bad out of box? I have not tried to bleed the abs unit yet. Any thoughts?

Faulty abs sensor I would guess.This complete troubleshooting guide will help you diagnose your brake problem.

Thanks @COROLLAGUY1. I’ll try to follow the chart. I was hoping the “whooshing” sound might point to something specific. Will an ABS problem cause the sound?

Try to record the noise and post it here.

It may require a scanner to bleed the ABS.

https://www.aa1car.com/library/abs_bleeding.htm

And anytime the primary brake warning light comes on, the ABS warning light will automatically come on.

The ABS is warning you that it’s not going to function as long as there’s a problem with the primary brake system.

Tester

@COROLLAGUY1, I will try to get one of my daughters to use their phone to record sound. My cell only calls people. lol.:older_man:

@Tester, right now, the brake light warning is off, just the abs warning is lit. I’m going to try to clean the front sensors. I think the rear might be more than I can handle due to its location. Guess I’ll have to bite the bullet if cleaning doesn’t help. I have enough brake to make it to Auto-Zone or O’Reilly’s. They advertise free use of a tool to read trouble codes. I’ll find out.

You’re going to need more than just a code reader.

This requires a full-blown scanner such as this.

https://www.cnautotool.com/goods-1568-GM+Tech2+GM+Scanner+-CANdi++TIS.html

And you may also need to buy the program key for ABS.

Tester

Thanks for the link. It’s right on the money, which by the way is “No Mucho” for me right now. I do understand the need for this tool. I was unaware of the program key (sigh).

I have a 1995 S-10. I disabled the ABS about 15 years ago, the first time it malfunctioned. I don’t miss it. Maybe try pulling the fuse for the ABS and see how the brakes work without it. I had the brake booster go out recently so I know what that sounds like. It normally alters your idle speed as well from the vacuum leakage.

Thanks @ChrisTruck! I will pull the fuse and give it a try. Yes my idle speed changes too. I’ll re-diagnose the Vacuum booster. It may be my reman was bad out of box. It’s a hoss to change. :cold_sweat:

I used the reman one Advance Auto sells. This was about a year ago and it still works fine so far. Except it comes unpainted and I didn’t have time to paint it and now it’s rusty. Immediately after I changed the booster, I was test driving it and the brake line burst while I was pumping the pedal…fun times.

The saga continues. With the engine off, I can pump the brakes up fully. With my foot on the brake, and starting the engine it sinks almost down to the floor. I drove it around the neighborhood while pumping and or holding the brakes. If I slowly press the brakes, they kinda stay pretty well up and occasionally the ABS light goes off. If I press them hard, the ABS light comes back on and I get the “goose honk” sound, (not to be confused with the whooshing noise) when the pedal is almost to the floor. Slowly stopping and pumping the brakes a little brings the pedal back up and the ABS light goes out. It seems that when I hear the “goose honk” the brakes try to come back.

I will now unplug the ABS fuse and see what happens. If my wife will stop throwing honeydo stuff at me I’ll try to inspect and or clean the front sensors and hubs. Stay tuned for further developments!

@COROLLAGUY1, @Tester, @ChrisTruck Hey all. Drove my truck to Advance Auto. They put their code reader on and it didn’t read anything. They said my “computer” wasn’t responding for unknown reasons. Oh well. I played with a few different braking senerio’s on my way home (8 miles). The ABS light stayed off and my brake pedal was pretty good. Stopping for at least six red lights, I only applied my brakes moderately and I had no problems. When I turned into my driveway, I applied the brakes firmly and they went down to within 1" of the floor. The ABS light came on. So, if it was a sensor, shouldn’t it stay on all the time?

I couldn’t find a specific fuse for the ABS. In the interior fuse box there is a fuse labeled brake (#18) but I don’t think that was it. I can’t find a fuse for the ABS in my old DIY repair manual. Does anyone have the memory of where it is? I still welcome any thoughts before I take my Sonoma down to my local service center. I hate giving up.:confounded:

I looked at mine again. It’s the brake fuse #18, there isn’t an ABS fuse. Just pull it and try the brakes. It’s not going to affect the brake system aside from disconnecting the ABS part. The ABS light will stay on after the fuse is pulled. At least this might show what problems the ABS is causing.

If you have the same OBD as mine (OBD 1.5), a lot of scanners can’t read it. It’s an OBD I system with an OBD II connector. I have a scanner that reads it. I’m not sure you can get any codes from the brakes anyway.

1 Like

There’s a lot of scanners that can read non-compliant GM OBDII codes.

You just can’t rent them from AutoZone.

Tester

1 Like

Thanks for the confirmation @ChrisTruck. I will pull #18 and road test.

I’m going to pull the front tires and check the ABS sensors this morning. I hope the port on the scanner connection isn’t bad. Thanks for the post. Not giving up yet!

For the whooshing and goose honking sounds, the brake booster seems where to look first. The brake booster puts some demands on the rest of the car’s vacuum system too, so if you have a vacuum leak elsewhere, the brake booster may not be the cause, just making the sounds louder. This seems less likely than a simple brake booster problem though. You can often use a length of old garden hose as a stethoscope to narrow down the source of a sound coming from the engine compartment. A hand-held vacuum pump gadget is a good way to test the integrity of the diaphragm of the brake booster. should hold vacuum to 20 inches at least.

1 Like

Hi @George_San_Jose1. Thanks for the reply! I have used a cardboard paper towel tube in the past, I’ll try it again. According to my old Haynes manual my truck is “supposed” to have 4 wheel abs. I pulled one of the front tires and I cannot find any sign of a sensor where it should be. So mine might just be rear wheel ABS. I re-bled all my brakes with no sign of air in the fluid. Then took it for a test drive and worked the brakes hard this time. Now I notice that when I release the brake pedal the brakes remain on for about a second or two. [I can feel the truck continuing to slow down.] In all my years, I have never experienced this before. When I press down and hard, the pedal goes down about 2 inches.

With the engine off, I can pump the brakes about 3 times and they pump up fine. While holding the pedal down and starting the engine, the pedal will sink down about 2-3 inches and I notice the RPM increases a little and the engine kinda struggles.

As in my original post, I did put on a re-man booster from Advance Auto and I wonder if it could be bad out of box. My my brake light does not come on but my ABS light comes on and off as I drive and casually stop and go. I have tried the trouble shooting guide posted earlier in this post and still have not come up with anything I can point my finger at. Could a bad booster cause my ABS light to come on? :pleading_face:

A flexible brake hose may have deteriorated over time and is collapsing when you let your foot off the brake pedal. If that’s what’s happening, the collapsed hose may be preventing the caliper from depressurizing immediately after you release the pedal, and so the brakes remain engaged. This is a somewhat common problem on older vehicles, from the reports here. Often when that happens one or more of the wheels will feel hotter than normal after a drive. Since braking is a safety issue, good idea to take you vehicle to a shop for a proper diagnosis. You may decide to fix the problem yourself once you know what it is, but a professional assessment is in order I think.