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Discussion Starter · #1 ·
Hey guys,

I'm having problems with my 2004 Rover 25 1.4 Petrol, Not much of a car guy but I thought I'd have a crack at fixing it.
Recently my amber engine light came up after a recent battery change and now I'm concerned to drive it. My OBD scanner can't connect but is getting power from pin 16. and the resistance of Pin 7 is 24.0k ohms, Firstly I don't know about how to go about making the OBD port work again and secondly whilst looking around in the engine bay I noticed continuous clicking in the fuel line and I'm not sure if I should be worried. Plus I found a loose connector and can't find where it goes?

Any help would be great.

Clicking sound >>

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Cheers
 

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rover_25
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That clicking sound is normal. its the idle air control vale making the noise dont worry about it, that multi plug is for the intake temp sensor which your car wont have.

Not all obd2 readers work on rovers theyre fussy on which ones they use.
 

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Discussion Starter · #3 ·
That clicking sound is normal. its the idle air control vale making the noise dont worry about it, that multi plug is for the intake temp sensor which your car wont have.

Not all obd2 readers work on rovers theyre fussy on which ones they use.
I think the engine warning light has made me very paranoid and aware of every little sound the engine makes now, just seems louder and longer than usual but thanks for reassuring me.
I've noticed the pins on my obd port only have a ground on pin 4 as apposed to pin 5. Would this cause not getting a data reading, and are you able to suggest a reader that would work with this model?

Many thanks
 

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2004 25 1.6
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Petrol MEMS3 cars are EOBD compliant and most scan tools should connect.
If you want something more advanced then obviously I will suggest pscan.
See Rover 25 MG ZR features
Yes only having only pin 4 will cause problems with some scan tools and the answer is to find a way to short 4 and 5. Maybe you can wrap some strands of copper wire around the pins of the tool.
 

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MG ZT, Rover 25
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The connector is for the gearbox speed sensor. As your's a late car, it probably has ABS which provided the speed signal. If it has ABS, the connector is redundant, just tie it up out of the way.

I'd be tempted to disconnect the battery for a few minutes, reconnect and see if a 'reset' helps resolve your other problems.
 

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Discussion Starter · #7 ·
Petrol MEMS3 cars are EOBD compliant and most scan tools should connect.
If you want something more advanced then obviously I will suggest pscan.
See Rover 25 MG ZR features
Yes only having only pin 4 will cause problems with some scan tools and the answer is to find a way to short 4 and 5. Maybe you can wrap some strands of copper wire around the pins of the tool.
I'll give that a go, thanks.

why on earth did they design the ports this way?
 

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Discussion Starter · #8 ·
The connector is for the gearbox speed sensor. As your's a late car, it probably has ABS which provided the speed signal. If it has ABS, the connector is redundant, just tie it up out of the way.

I'd be tempted to disconnect the battery for a few minutes, reconnect and see if a 'reset' helps resolve your other problems.
I see, I do have ABS so I will just forget about it then :)
I've already taken the battery out many times when testing the electrics, still the fault remains. I need to find out why the EML is on before I feel comfortable driving around again.

Thanks
 

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2004 25 1.6
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why on earth did they design the ports this way?
According to the standard pin 4 is chassis ground and pin 5 is signal ground. So unless they ran a ground wire from the diagnostic port to the ECU it is kind of correct to only populate pin 4.

MG Rover's design criteria would have been:-
1. Does it work with the dealer T4 diagnostic tool?
2. Does it meet the letter of the law on EOBD tools?

If yes and yes then job done. They really wouldn't care if it works an any one specific diagnostic tool that you or me might buy.

If this doesn't work then you will need to check connectivity from pin 7 to the engine ECU. I can help with that if it comes to it.
 

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Discussion Starter · #10 ·
According to the standard pin 4 is chassis ground and pin 5 is signal ground. So unless they ran a ground wire from the diagnostic port to the ECU it is kind of correct to only populate pin 4.

MG Rover's design criteria would have been:-
1. Does it work with the dealer T4 diagnostic tool?
2. Does it meet the letter of the law on EOBD tools?

If yes and yes then job done. They really wouldn't care if it works an any one specific diagnostic tool that you or me might buy.

If this doesn't work then you will need to check connectivity from pin 7 to the engine ECU. I can help with that if it comes to it.
True, I just thought I was being clever buying a cheap obd2 scanner. :)
Are you able to give some advise on what I should be looking out for with pin 7 in terms of volts and resistance?
 

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2004 25 1.6
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The problem is that quite a number of the Rover 25 ECUs are all connected to pin 7 on the 16 pin diagnostic socket, specfically I think that the ABS, Pektron SCU, airbag and engine ECU are all on the same pin.

A problem with any of those ECUs, or with the wiring will stop the diagnostic tool connecting to the engine ECU.

The engine ECU on its own will connect the K line (through a pullup) to +12V when the ignition is switched on. Shorting from the K line to earth will pull about 11mA.

You may have to disconnect all of the other ECUs so that the engine ECU is the only one on the bus.

or it might be that your scanner is not compatible.
 
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