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Over the last 8 months, the car has read a code of “Short or open circuit Right Front Wheel Speed Sensor”(something like that). We replaced the RF wheel bearing hub assembly. It worked perfectly for about 3 weeks and then the same issue came up(pretty well the same). This time, instead of them being on as soon as you turn the car on. They come on when the car hits a bump, or sometimes even after 20 feet of driving.
Is this another faulty Wheel Speed Sensor, or should the wiring harness be replaced? (Note: The bearing itself is perfectly fine.)
The wiring near the control arm seems to be fine, and not pinched, or broken.
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First tell me what kind of equipment you have access to. My assumption would be a multi-meter, but not a scope or scan tool with ABS live data…is that correct?
Currently, I have access to just hand tools. I had it scanned previously at the place I worked(which I no longer work there) and got them to scan it again once the issue came back up.
At my own shop, I just have basic tools. I’m pretty young, and still working on my tool set.
Ok I feel that at the bare minimum you will need a multi-meter in order to investigate this problem. It’s cheaper in the long run to invest in diagnostic skills and equipment than to swap parts. I’m glad to hear that you’re investing in hand tools, but I find my multi-meter gets used at the same frequency as many of my hand tools. I really don’t know what I’d do without one.
You can get a multi-meter pretty much anywhere (even wal-mart). If you want to make an investment in a nice multi-meter then I would suggest a BK Precision 2709B. I think this is one of the best multi-meters for the cost I’ve come across. To really get into what makes a multi-meter much better than another one I’d probably have to write too long a post, but the short answer is things like speed, min/max function (really useful for automotive), lightning quick continuity beep, backlight that doesn’t time out too quickly. Those are just a few. Unlike many many multi-meters out there I can tell that the person who designed the 2709B really understands the type of functionality needed in the real world.
Whatever you end up with…I feel that we will need to get some hard evidence (via electrical testing) before any of us could give you any further advice.
GM cars of that design still use 2 individual wires for the ABS sensors, as opposed to the 2 wires in a single insulator that most other ABS systems use. This makes them very susceptible to breaking along the control arm up to the subframe, where they no longer move with the suspension. These wires will be in the cheap plastic wire sheathing.
Unplug the sensor terminal, remove the sheathing from the wires back to the subframe and look for breaks. Repair any breaks and go from there.
[quote=”DaFirnz” post=181552]GM cars of that design still use 2 individual wires for the ABS sensors, as opposed to the 2 wires in a single insulator that most other ABS systems use. This makes them very susceptible to breaking along the control arm up to the subframe, where they no longer move with the suspension. These wires will be in the cheap plastic wire sheathing.
Unplug the sensor terminal, remove the sheathing from the wires back to the subframe and look for breaks. Repair any breaks and go from there.[/quote]
I was reading that any splicing could cause incorrect signals, and not to do that. This was on another forum page.
[quote=”DaFirnz” post=181552]GM cars of that design still use 2 individual wires for the ABS sensors, as opposed to the 2 wires in a single insulator that most other ABS systems use. This makes them very susceptible to breaking along the control arm up to the subframe, where they no longer move with the suspension. These wires will be in the cheap plastic wire sheathing.
Unplug the sensor terminal, remove the sheathing from the wires back to the subframe and look for breaks. Repair any breaks and go from there.[/quote]
That’s great info! Let me also add that the copper strands can actually break inside the insulation. One way to test for this is to give them a good tug in different locations and see if you notice the insulation stretching anywhere. Since your problem is intermittent you may not see a full blown broken wire, but rather some very very small break that is intermittently making connection…so look very closely. Also please report back what you find. A lot of people on forums never come back and finish the thread with a conclusion.
[quote=”nightflyr” post=181560]Just something else you may want to look at …
Check the tone ring.[/quote]Yeah that brings up a good question. I had assumed that when he said bearing/hub assembly he was referring to the gm style with an integral tone ring since he replaced the whole bearing assembly just to address a sensor issue. But for clarification is your tone ring external (i.e. on the axle) or is it inside the bearing along with the sensor? If it’s actually external then look at the teeth on the tone ring and see that they are uniform and free of rust or other ferrous flakes & chips. Also if you do have an external tone ring and sensor the air gap is absolutely critical. VRS rely on magnetic field strength which is exponentially proportional to distance (I believe I’ve got that right). What that means is a small amout of change in distance greatly changes magnetic field strength. Anyway, increasing the distance even like 1mm or less from spec can cause the signal to be too weak for the computer to read at low speeds. Rust jacking of the sensor is a common cause of too much air gap.
It has an internal wheel speed sensor, I’ve already looked into that too.
You can’t really check the internal ring without tearing the hub assembly apart. Which I’ve considered doing to the old one just to see if it was bad, but the problem being if the tone right was good on the old one, you can’t really put the hub assembly back together and would be useless(bearing on the old assembly was still perfectly fine, with no play)
Ok that’s what I figured…although new parts are sometimes faulty the chance of that is so small that I think you really need to start focusing on wiring integrity. Since you put in a new hub/bearing with a new sensor inside of it then like I said I think it’s time to start focusing on wiring.
I was looking at that exact same thing today.
Does anyone know how hard it is to remove and replace the old wiring harness on these GM platforms?
Since the sensor is in the front the wiring should be pretty accessible…just follow it into the engine compartment and see where it goes. It doesn’t look like that replacement harness is made to replace all the wiring from the sensor to the ABS module but rather the wiring around the knuckle (which is usually where breaks occur)
Yo don’t need to got through the main harness, just the outboard wiring going from the subframe to each sensor. that is where the breaks happen. The replacement ‘end’ is designed to replace that part of the wiring.
Not saying that’s definitely your problem, but I’ve seen more than enough broken wires going to GM ABS sensors, it worth the 30 minutes to take a look at.
Start by unplugging the sensor and removing any sheathing or tape all the way back until you make it into the wiring that’s secured onto the subframe.
Alright, so another typical issue known with these cars(the engine). We’ve noticed some excessive leaking of coolant just over the transmission from the lower intake manifold. Almost getting to the point that it’s not worth fixing. It hasn’t been overheated, and always topped up with coolant when low. It currently has 185,000 KM’s(110k miles). I feel like I’m not skilled enough to get that deep because you have to pull out the push-rods. It’s a costly repair. Most shops are asking for $900-$1200.
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