2006 M45 possible speed sensor issue

Post by **raven69david** » Mon Dec 13, 2021 8:02 pm

I just purchased a used 2006 M45 for $1,000 that has some problems. I just replaced the downstream O2 sensors as the secondary cats had been stolen and they cut the O2 sensors off(I plan to patch them up in a few days). I have also replaced the alternator, as it was dead, and added new drive belts as they were worn. The initial issue with the car is that it idles very rough, which could be due to missing cats, but the car barely drives down the road. When I put it in D and take off, it will barely shift from 1st to 2nd. Once it does shift to 2nd, it will be during high RPM. It does not seem to want to go faster than 20 MPH down the street so I'm thinking it may be a speed sensor. The previous owner tried to resolve the issue by replacing the ECM, but that didn't work. When I try to use a scan tool (Carly), I will get a message that states that no ECM is found. If I use it on a different vehicle, the scan tool works fine. Since I can't scan for codes, any suggestions on where to start? I don't want to start throwing money at the vehicle blindly hoping to fix it as I'd rather find the problem and repair it using the proper OEM parts. Thanks in advance.

Post by **VStar650CL** » Mon Dec 13, 2021 8:27 pm

If the car runs then the ECM is alive, so the first thing should be to find out why your scan tool can't read it. Both of the power lines on the DLC connector are fused, one battery and one ignition. If either one is blown, most scanners won't connect properly.

Post by **raven69david** » Mon Dec 13, 2021 10:11 pm

VStar650CL wrote: ↑
Mon Dec 13, 2021 8:27 pm
If the car runs then the ECM is alive, so the first thing should be to find out why your scan tool can't read it. Both of the power lines on the DLC connector are fused, one battery and one ignition. If either one is blown, most scanners won't connect properly.

Thank you. Where would I locate the fuses? I’ve gone through most of the fuses in the car and none were blown. I may have missed a location or two so I can check any areas you suggest.

Post by **VStar650CL** » Tue Dec 14, 2021 5:42 am

They should both be in the inside fusebox, but use a lamp to check them and not a visual inspection. That way if any are cold with the key that should be hot, you'll know you have a problem upstream with a relay or wiring.

Post by **EniGmA1987** » Tue Dec 14, 2021 8:28 am

I would go and get a look at the ECM and take a picture of the model and serial. Try looking it up and ensure that it is an actual OEM part and the correct part for the car. Going by the issues with the car and the price, you really can't be sure yet that it has an original model ECM in it instead of some cheap aftermarket. This would be a quick thing to check and doesn't cost money, and it's good to know you have the proper equipment in there before anything else.

YouTube · Post by **EdBwoy** » Wed Dec 15, 2021 9:19 am

I want to go out on a limb and say that if your gauge cluster is displaying the vehicle speed, then your speed sensors are fine.

Wheel speed sensors don't typically affect the engine in any way. And if they have issues, the VDC light should also be on. The transmission speed sensor doesn't usually do that either, although it come into play as to when the transmission decides to shift gears.

I feel like you are describing a transmission issue because the car is speed limited. Most times engine issues are RPM limited. You could actually have both, but it's going to be tough to go anywhere without usable codes. If you can't get the OBD2 port to read, I believe there is a way to do a pedal dance to identify codes by the number of times things flash on the cluster - not efficient, but better than nothing I suppose.

***
My advice would be to hold off on buying anything to replace damaged parts, because you might find yourself in a similar position as the previous owner. Maybe the real problem is somewhere else - for example it could be running rough because of a misfire, and as a result it went into a failsafe where the output is limited.
Try the troubleshooting steps that don't cost money, such as disconnecting the coil packs individually to isolate any misfiring issues localized at a cylinder.

Post by **raven69david** » Wed Dec 15, 2021 12:32 pm

EdBwoy wrote: ↑
Wed Dec 15, 2021 9:19 am
I want to go out on a limb and say that if your gauge cluster is displaying the vehicle speed, then your speed sensors are fine.

Wheel speed sensors don't typically affect the engine in any way. And if they have issues, the VDC light should also be on. The transmission speed sensor doesn't usually do that either, although it come into play as to when the transmission decides to shift gears.

I feel like you are describing a transmission issue because the car is speed limited. Most times engine issues are RPM limited. You could actually have both, but it's going to be tough to go anywhere without usable codes. If you can't get the OBD2 port to read, I believe there is a way to do a pedal dance to identify codes by the number of times things flash on the cluster - not efficient, but better than nothing I suppose.

***
My advice would be to hold off on buying anything to replace damaged parts, because you might find yourself in a similar position as the previous owner. Maybe the real problem is somewhere else - for example it could be running rough because of a misfire, and as a result it went into a failsafe where the output is limited.
Try the troubleshooting steps that don't cost money, such as disconnecting the coil packs individually to isolate any misfiring issues localized at a cylinder.

Thanks Ed. I've been going through all of your videos to see if I can find something similar, but found none. I'm thinking about putting the original ECM back on to see if it'll finally show codes. In the meantime, I'm going to check all the coil packs and see if there are any cracks or obvious signs of wear or arching. The valve covers were recently replaced but not sure what else was done to the vehicle. The previous owner broke a lot of tabs in the engine bay when looking around it.

Also, I'm unable to access the climate control or stereo buttons. I took a picture of the wires in the center console and they just don't seem right. On my previous M45 and M35 the same issue would occur when I would disconnect the cables underneath the center console tray just below the HVAC controls for the seats. Thoughts? Unfortunately I can’t post pictures on here.

Post by **raven69david** » Wed Apr 06, 2022 1:11 pm

Replaced ECM and now most of the issues are gone. The only issues that remain are p1168 (looking for o2 sensor recommendations) and I still don't have power to the AC panel or stereo. They light up at night but they don't have any functionality beyond that.

2006 M45 possible speed sensor issue

2006 M45 possible speed sensor issue

Re: 2006 M45 possible speed sensor issue

Re: 2006 M45 possible speed sensor issue

Re: 2006 M45 possible speed sensor issue

Re: 2006 M45 possible speed sensor issue

Re: 2006 M45 possible speed sensor issue

Re: 2006 M45 possible speed sensor issue

Re: 2006 M45 possible speed sensor issue

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