Strange speedo combined with limp mode issue

[JACKO5]

Morning all,

I am hoping for a bit of help with this little problem. I have done a search and found the speedo sensor issues, but am yet to find one with exact matching symtoms to mine. The car in question is a 2002 172. Ok, so when driving, every now and then the cars speedo with drop to zero. This is also met with the car going into what i understand to be limp mode. The engine wont rev over 4k rpm. It will stay like this for some times seconds, sometimes a few miles, and then speedo reading will return and full revs return. This is occuring sometimes daily, then other times will be fault free for upto a week. I have removed the tdc sensor and speedo sensor and cleaned them both up. Put them back on the car. But as the fault is intermittant i cannot pin point it down to one particulaar area. I'm awaiting a work mate of mine bringing his code reader into work so i can try and have a look there, but i thought it can't hurt to see if anyone on here has had the same problem.

Thank you for looking, and any advice offered will be gratefully accepted.

Have a good day.

 

[Cooksport]

Jacko5,

Have you checked the battery connections and engine to body earths? Your fault is different to a normal speedo fault as the engines rpm is not generally affected.

Do any fault lights show up when the fault occurs? If not I dont think you will see a recorded fault on a reader.

Id check/clean battery terminals (make sure you have your radio code) then look at the engine earth strap that runs from the left side of the gearbox to the chassis leg. There is also a smaller wiring loom earth attached above the left hand driveshaft.

Are there any other symptoms you experiance? Bad starting/driving issues?

Hope this helps

Mike
Cooksport

 

[JACKO5]

Mike,

Cheers for the reply. I have checked the battery connections. They seem to be good. I will check the earthing connections. No other faults occur at the same time, and starting and driving are both fine. All other electrics seem to carry on functioning as normal. Also no fault lights show up on the dash???

I spoke to someone at ktec who mentioned something about the abs rings are also used to send a speedo signal, so potentially this could also be the problem area. I haven't checked this avenue yet tbh. Just thought i'd see if anyone else has had the same issue and resolved it. But this seems to be a new electrical fault!!!

Rich

 

[Cooksport]

Hi Rich,

If your car has a speedo drive, i dont think the abs rings are used for speed input.

Bit of a weird one this, if you check the earths and its still a problem give us a call as its easier to go through it all.

07759 437181

Thanks

Mike

 

[Dan519]

Jackson, just call me. Your fault is without question the speed sensor. Told Deacon it needed changing. It's only £25

 

[JACKO5]

Hi Rich,

If your car has a speedo drive, i dont think the abs rings are used for speed input.

Bit of a weird one this, if you check the earths and its still a problem give us a call as its easier to go through it all.

07759 437181

Thanks

Mike​

Cheers Mike. I am going to check the earths this evening to make sure they are ok.

Jackson, just call me. Your fault is without question the speed sensor. Told Deacon it needed changing. It's only £25​

Cheers Dan. Deacon failed to mention this to me when i said to him about the problem! Typical Deacon.

So does the speedo sensor fault commonly cause the kick in of limp mode as well? I have done a fair bit of looking and couldn't see a mention of the limp mode kicking in as well as no speed reading for anyone else. Not that i'm doubting your response. I will be on the phone in the morning. Are you working tomorrow?