Our 2001 Jeep Grand Cherokee has 150,000 miles on it. Lives in a temperate climate, has had all maintenance along with oil changes every 3500 miles and it has never been problematic. A couple months ago the ABS light came on and we had it scanned by one of the few dealerships in our area that can still do this on an older car.
Scanner said that the front driver side speed sensor was bad, so replaced it. Light stayed on and the next scan said the ABS pump was bad, but the ECM was OK. Couldn't find a new pump so bought a used one and had it installed.
The light stayed on, another scan. This time it is the electric motor. Pulled it out and sure enough the motor was hardly running, screeching and rough. Had to buy yet another ABS pump to get a motor. It ran like new, so had it installed. Still doesn't work. Had the mechanic test to see if electricity/power is getting to the motor, and it is. There is nothing wrong with the wiring.
Had it scanned yet again and it says the pump conduit is bad. No idea what this means.
Throughout this process we have retained the original ECM because it's our understanding it is programmed to work with the vehicle and a new one would need to be flashed if that is the right terminology. Not sure anyone around here can even do that. So at this point it is the only part that has not been replaced.
We know that the car will run just fine without ABS, but having come this far I would really like a solution. Any ideas would be appreciated.
Huge, huge fan.
why isn't all this information presented at once
that's just how it goes sometimes. a simple deck repaint turns into replacing a few boards, which turns into reframing a section, which turns into ...
was told it is the pump electrical circuit.
the fault in the circuit needs to be found and repaired. If this mechanic isn't up to it find another one.
I am just trying to figure out why it is that we fix one thing and then the scanner immediately flags something new?
You have to expect these things when dealing with a 25-year-old vehicle. Frankly as a car gets older and older it becomes less feasible to own it if you cannot work on it yourself. If you have to keep running to mechanics for every problem it can quickly become an expensive headache. Then, even if you do your own repairs you still have to deal with the problem of sourcing parts that are not made any more.
Also, scanners do not give you a list of parts to replace. (I'm not sure where that commonly-held misconception even comes from.) Scan tools tell you that conditions exist that usually have several potential causes. Further diagnosis is required to actually zero in on the problem(s). Such diagnosis may consist of bidirectional testing of components using a sufficiently sophisticated scan tool and/or physically checking wiring and components.
You could be looking at any number of faults due to deteriorated wiring and electronics. Don't forget to check all the grounds. Bad grounds cause all kinds of crazy problems.
Is that how it typically works, in a sequential fashion vs a global one?
sometimes. When you fix one broken link, then the load is transferred to the next weak one. Sometimes, you are only seeing symptoms. You whack one symptom and another pops up until you discover the root cause that's really causing all of them. Point being, auto repair is often a process of discovery. You COULD take nuclear or "global" approach as you call it, and tear everything apart. But sometimes that's inefficient, you end up replacing things your don't need, and people get angry about the money spent/wasted. Most people like doing one thing at a time. Certainly, I'm not discounting the possibility that the mechanic is simply not great at his job. Did he provide you with the trouble codes the scans were reporting? Did he show you what was broken?
We are being charged $125 for every scan.
And this is why Scotty vigorously encourages everybody to buy their own scanner. They are so cheap, and they can save you thousands of dollars. You can get a pretty decent one like Bluedriver for only a hundred bucks.
There are folks in the area that specialize in auto electrical problems.
perfect. this sounds like a job for them
When you say the circuit needs to be found and repaired does that mean the wiring harness or are there other things involved?
Basically, "yes". There's isn't enough information in this forum post for me to narrow this down further. This is a hands-on, eyeballs under the hood, multimeter out kind of situation.
New here and can't find a way to edit my post. Want to amend the last statement--it was not the "pump conduit" as reported. Spoke to the mechanic and was told it is the pump electrical circuit. One thing I don't understand...why isn't all this information presented at once versus something new popping up with each repair?
Thank you for your input. I think you are right. Our regular mechanic retired and his son is not quite as experienced. Probably time to make a change.
But as far as the renovation analogy, a deck doesn't have a supposedly sophisticated computer system attached to it ;). I am just trying to figure out why it is that we fix one thing and then the scanner immediately flags something new? Is that how it typically works, in a sequential fashion vs a global one? I thought it would flag all issues, versus one at a time. I just want to have an idea so that I have appropriate expectations. We are being charged $125 for every scan.
There are folks in the area that specialize in auto electrical problems. When you say the circuit needs to be found and repaired does that mean the wiring harness or are there other things involved?
Again, many thanks for the reply.
Thank you! I am just trying to narrow things down and understand how this works, so your explanation is very, very helpful.
We do have a couple scanners but they are for our GM or Japanese/Toyota cars. We have held onto the Jeep for mostly sentimental reasons, but it has not cost a lot to operate. We have done all the maintenance and regular oil changes and it has perked along with no issues. Isn't a daily driver, but we like to have a 4x4 on hand and it fits the bill.
We called the electrical specialists and they sounded confident that they could track down the issue. Thank you SO much for taking the time to explain.