rev counter (not digital )

[pablo0874]

morning all , i have touched on this before but was wondering if anyone can shed some light without me being referred to the manual which doesnt give much away ,i need to know what the little bugger is that operates my rev counter ,as ive had this rev counter intermittent problem for a long time and mil light comes on when rev counter down but still very driveable im just fearing that one day this wont be the case so am looking to get the replacement part of said ,rev counter operation ,
now i have been advised reviously about ckp sensor in the front under the thermo housing is this the correct part does anyone know??
i seen one on ebay last week but the seller would nt tell me wether this operates the rev counter ,not sure if he knew ,has anyone had this problem aand whats the cure ,:thumb2:thumb2

 

[makeitfit]

Not sure really mate. However when I had Crank position sensor probs, I had no issues with the rev counter

 

[pablo0874]

Not sure really mate. However when I had Crank position sensor probs, I had no issues with the rev counter

its baffling then as know one seems to know why the rev counter goes on and off and cant point me in direction of what operates it cheers anywwy:clap

 

[makeitfit]

Sorry mate the rev counter must be one of the few things I've not had to modify, change or fiddle with in any way :lol Result

 

[briggie]

page 73 gives a wiring diagram which seems to include the tachometer

http://bebrs.pie-dabas.net/Webs/Terrano/R20/el.pdf

 

[rayf3262]

The CKP or crank sensor senses both the rotation & position of the crankshaft by a toothed wheel/cog.

This signal goes directly to the ECU and nowhere else.

The ECU uses this signal to measure the engine speed & establish the correct timing.

The ECU sends out a derivative of the CKP signal to the dash unit where it is used by the rev. counter.

Given the ECU is throwing up the MIL occasionally, you probably (most likely) either have a loose connection from the CKP to the ECU.

For what it's worth, CKP's are not generally know for being intermittent, but do tend to misbehave when aged and coupled with being hot.
When the CKP signal "dies" (due to a poor connection) for a short time the ECU will use the timing signal from either the No1 injector or the IP, but will still throw the MIL.

 

[Timbo_1975]

The CKP or crank sensor senses both the rotation & position of the crankshaft by a toothed wheel/cog.

This signal goes directly to the ECU and nowhere else.

The ECU uses this signal to measure the engine speed & establish the correct timing.

The ECU sends out a derivative of the CKP signal to the dash unit where it is used by the rev. counter.

Given the ECU is throwing up the MIL occasionally, you probably (most likely) either have a loose connection from the CKP to the ECU.

For what it's worth, CKP's are not generally know for being intermittent, but do tend to misbehave when aged and coupled with being hot.
When the CKP signal "dies" (due to a poor connection) for a short time the ECU will use the timing signal from either the No1 injector or the IP, but will still throw the MIL.

If I can just refine what Ray said alittle bit- the ECU requires a working signal from the CKP for starting. If this then fails or goes la-la whilst the engine is running it will NOT cut out, but LOS mode will apply. There is quite a large window of error the ECU will tolerate, so you will experience some strange running issues unless the sensor fails altogether.

 

[rustic]

I have read on here ( I think) that the CKP sensor is magnetic and it deteriates with age and heat, so it could be loosing magnetism, and it is worse when it gets hot.
So it might only just be working. After all, if yours is the original it could be 10 years old.

If you could find another vehicle of the same type, you could swap them to see if the fault moves with it. :nenau

Just a thought..

PS don't have all these things to go wrong on the 2.7Td..

 

[MudLifeCrisis]

morning all , i have touched on this before but was wondering if anyone can shed some light without me being referred to the manual which doesnt give much away ,i need to know what the little bugger is that operates my rev counter ,as ive had this rev counter intermittent problem for a long time and mil light comes on when rev counter down but still very driveable im just fearing that one day this wont be the case so am looking to get the replacement part of said ,rev counter operation ,
now i have been advised reviously about ckp sensor in the front under the thermo housing is this the correct part does anyone know??
i seen one on ebay last week but the seller would nt tell me wether this operates the rev counter ,not sure if he knew ,has anyone had this problem aand whats the cure ,:thumb2:thumb2

Hope someone can answer this as mines been doing the same for years ;O(

Two mechanic friends have said its a earth fault with the alternator,Checked every connector with no joy .

Mine started after jet washing the engine bay ;O)



Brian

 

[Timbo_1975]

I have read on here ( I think) that the CKP sensor is magnetic and it deteriates with age and heat, so it could be loosing magnetism, and it is worse when it gets hot.
So it might only just be working. After all, if yours is the original it could be 10 years old.

If you could find another vehicle of the same type, you could swap them to see if the fault moves with it. :nenau

Just a thought..

PS don't have all these things to go wrong on the 2.7Td..

The CKP or CAS is a ferite core with a *very* fine wire wound around it mounted perpendicular to the rotating 'teeth' on the flywheel. It's a two-wire passive component and you would expect to see a squarewave output from it, amplitude (volts) directly proportional to engine speed. At cranking I would expect a minimmum of 2.5v. At 4000rpm it could be as high as 30v. The often fail completely when hot due to the coil breaking after so many heating and cooling cycles. A quick zap of freeze spray will often restore operation.

The flywheel on these doesnt have a missing tooth like most do, which are known as a '60-2' . Another useless bit on info concerning these are that new Ford ones come with a plastic tip which you install against the flywheel. When you start the engine the tip breaks off in just the right place to leave the ideal air-gap.