ABS DTC C0221

[east302]

Truck is a 1998 K1500.

I have a C0221 code for an open right front wheel sensor.

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Following the GM diagnostics, the resistance is within spec. Next step is to check for any bad connections and, seeing none, replace the EBCM.

I can get the ABS light to go on and off by either pushing up on the connector or pulling the tan wire forward toward the front of the truck.

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I checked the resistance in the green and tan wires using a meter connected at the EBCM connector and the wheel speed sensor connector. Both were at 0.1 to 0.2 ohms with me wiggling the wires as much as I could.

The pins in the EBCM end of the connector feel solid, not loose. Could this be a broken solder at the pin inside the EBCM? Not really sure where to go with this short of replacing the module. What do y’all think?

This is on our son’s truck, so my preference would be to keep the ABS.


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[alpinecrick]

Given your description have you checked the connector? I had somewhat similar situation with one of the connectors for the neutral safety switch for the trans. The wire and one of the pins inside the connector was screwed up.

 

[east302]

I didn’t take the actual connector apart, but everything looks clean on it- no corrosion and the wire insulation is solid. Guess it wouldn’t hurt to try to pull it apart and see how it is on the inside.

Checking continuity at both ends of it showed nothing. It always showed some resistance no matter how much I moved the wires around.

 

[Schurkey]

This would be better posted in Axles + Brakes rather than Engine Performance + Maintenance. Perhaps a moderator will move this thread.

Subscribed. My '97 K2500 has the same situation on the LF sensor. Sensor and harness seems good, but computer can't "read" it.

 

[east302]

Swapped the EBCM out with a good one from another 98 that I have. The code cleared and I was able to do the ABS bleed.

I’m not sure how you even get into these 310 units. I’m curious as to what went wrong with it. The later ones at least have screws on it. I guess I’ll gamble with one for a junkyard. It seems that the normal rebuild companies don’t even work on these.

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[alpinecrick]

It's good you figured it out! Usually it's the wheel sensor. I think I have one sitting around off of a 97 Suburban, but I'm not sure if they are programed differently for different models and years.

 

[east302]

I think they’re the same for 95 up to the 2000 Escalades, so I’m planning on looking for the newest one that I can find to put back in my truck.

The problem is that whenever I go to the junkyard I end up buying other extra things. Kind of like Walmart I guess.

Sidebar, then. This ABS is on my son’s truck. The one I pulled the module off of is “my” truck that I put maybe 1,000 miles a year on. Is the ABS delete really the bees-knees on these? I didn’t want a teenager without ABS but wouldn’t mind dropping it on mine if it saved me some headache and money trying to find a functioning 20+ year old module in a salvage yard.

 

[Schurkey]

Don't get into a collision and then have the other guy's lawyer find out you disabled the ABS on your truck.

 

[east302]

Thanks, I’d agree with that. Swapping the module only takes a minute or two, going to go shopping for another one.

 

[spitanddirt]

Swapped the EBCM out with a good one from another 98 that I have. The code cleared and I was able to do the ABS bleed.

I’m not sure how you even get into these 310 units. I’m curious as to what went wrong with it. The later ones at least have screws on it. I guess I’ll gamble with one for a junkyard. It seems that the normal rebuild companies don’t even work on these.

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I pulled a junkyard ABS module apart just to learn about how they function.

The super short version about why rebuild companies won't touch them is because the unit is sealed with a small amount of vacuum and some extremely tough encapsulation epoxy.

They have a small packet of desiccant under the black cover, which, by the way, is not able to be removed without completely destroying it. The black plastic is very frangible. It is very stiff, and has a lot of internal reinforcement when it's glued to the aluminum case/frame. The problem is that even after carefully removing as much of the epoxy encapsulation compound as possible, the black cover is still glued to the aluminum case with a substantial amount of encapsulation.

The good news is that the electronic unit is very robust and uses top quality components. The likelihood of broken solder joints is always a possibility, but from what I observed, a lot of care and consideration went into designing and implementing the Kelsey-Hayes ABS module. ABS functional problems after all these years are usually attributed to the contamination and subsequent blockage caused by the rusting from the inside of the steel brake lines.

Btw, the main microprocessor used in the 1999ABS donor is made by Intel. You can even see the copyright date of 1998 on the chip. The function of the smaller chip to the right of the largest is so that the ABS can communicate to the ECM. It's a SAE J1850 10.4K VPM compliant chip made by Motorola. GM service manuals call it "Class 2 Serial data." Everything else on the board was sourced through top tier U.S. based semiconductor companies. There are also Atmel chips, and Kemet capacitors.


I'll be making a Separate post in axles and brakes about teardown of the ENTIRE ABS module.


If someone were to diagnose and repaire these ABS control modules, they should just count on designing and manufacturing NEW 3D printed covers every time they rip one off.

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