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Rev counter and EPAS

5K views 13 replies 6 participants last post by  Julian Foulger 
#1 · (Edited)
Good morning.

On my X plate Steptronic 'F' the rev counter and power steering are both inoperative, but will occasionally spring into life.

I recently changed the ECU and 5AS, but that shouldn't be the cause of the problem as the power steering had the same issue before the change. Admittedly, I didn't notice the rev counter issue before, as the car had been garaged for 10 years and not driven out on the road where it would have become obvious.

Any ideas? Is there any link between these 2 that might be faulty, but which doesn't affect anything else?

Rab
 
#2 ·
Been away from the forum and the car for a couple of weeks. Surprised to find that there has been no response to my earlier post, but linking the 2 faults may have made it too complicated, I suppose.

The car seems to be running fine other than these 2 problems which occur simultaneously. Could there be a wiring problem or is there a faulty relay or other component that might affect both functions???

Anybody able to advise re the likely cause of the intermittent EPAS problem, please.

Likewise anybody with advice re the likely cause of the intermittent Rev Counter problem would be appreciated.
 
#3 · (Edited)
I do not have experiance with EPAS so I cannot advise on it.
Regarding rev counter it could be sensor, wiring, connector or counter itself.

EDIT: Connection between EPAS and rev counter can be in Egine speed signal which is the only connectiong point. This signal is coming from Engine control module (engine ECU) and is used for rev counter but is also jsed with EPAS. Might be worth to check this wiring or connector? In the engine bay? It is white wire with black stripe on pi 55 on the engine ecu.
 
#4 ·
Hi Rab.

Sorry I don't have an answer to your question but what I do know is that the EPAS cuts out if the engine is revved at 2500 for over 30 seconds
whilst the wheels aren't turning. The MOT guy failed me for this although it's standard system procedure.

So it could be related to this MGF 'feature'.

Does it happen when driving or just at a standstill?
 
#5 ·
EPAS takes its a signal from the rev counter. It operates by taking inputs from various sources including from the tachometer (rev counter) for engine rpm. If rev counter does not send any signal to the EPAS, the EPAS may switch off on basis that there is a fault beyond the ECU's mapping.

As I have had my car since new (1998), I have had an issue with the rev counter in the past. Check the white and black single wire from the ECU to the instrument cluster is fully connected / not broken or damaged.
 
#6 ·
Didn't see your original post, and maybe this has been covered as this was a relatively common and well known issue with those two issues normally connected. Have you checked the speedo cable and the connections along it and also its connection to the back of the binnacle?

If any of the connections along it, three I think from memory, are not connected then the rev counter won't read and (with the MGF - it works differently on the TF I believe) the EPAS will not work, as said above, the EPAS will turn off, eventually, if it isn't getting a signal of speed.

I've had this myself in the past and it was just the connections in the cable loose. If there is some connection it will be an intermittent problem, from memory the EPAS would work randomly for about ten minutes sometimes when the car was started before shutting off (I took the fuse out in the end until it could be fixed to shut it off completely as it was a little unnerving to sometimes have it and sometimes not).

More at http://www.mgf.ultimatemg.com/group2/DIY/Speedo_cable/
 
#7 ·
Thanks for the replies.

The light that indicates the boot is open has suddenly started to illuminate despite the boot being closed. Sometimes the light is very dim, other times it is full on. Comes and goes. On checking the wiring to the boot, it is obvious that there is some melting of the cables attached to the near side boot hinge (7 thin cables wrapped together). This small bundle of cabling goes into the engine bay above the petrol filler neck and is then attached by tape to a much larger bundle. It looks like the melted section of cabling doesn't go as far back as the larger bundle (fingers crossed). Currently (excuse the pun) stripping it back to find out the full extent of the damage. Hopefully when reinstated that will solve the other issues.

What's the odds???????

Rab
 
#9 ·
Repairing the boot loom would be a good start as it can cause a few problems. My loom was badly damaged but it didn't cause the problems you describe. A blown fuse or bad connection will put the boot open light on. Fuse 11 (under the dash) on the TF may not be the same on the F. Don't know. Do the foot well lights and radio work OK?
 
#10 ·
Boot hinge wiring

Thanks again guys. There is a sticky referring to problems with the wiring at the boot hinge and I have found that the wiring is completely destroyed at that point with some burnt/broken wiring inside the flexi hose that protects 7 wires held inside. The worst affected wire is a purple coloured one which has melted from the boot hinge to under the dash behind the radio (I can't get any further yet). There doesn't appear to be any damage to other wires within the loom up to that point, as I have removed all of the plastic clips, tape, fasteners to try to establish the full extent of the problem. One single wire seems to be causing havoc, but there might be other wires affected behind the dash.

It looks like a dashboard removal to find where that wire eventually goes!!!!!!!

Having read StevieJones133 recent thread, I confirm that I had many of the symptoms that he refers to, including the blown #12 fuse. Replacing the original blown fuse did not result in another blown fuse which led me to think that it was just a one off. I had to replace the whole fuse box as the area around #12 fuse had melted. Before and after the fuse box was replaced there did not appear to be any problem as everything appeared to work normally until the rev counter/EPAS/bootlid light issues. There is no sign of wiring damage to any of the connectors going to the fuse box under the steering wheel (there is only 1 purple wire connected to the fuse box but it is thicker than the burnt one in the boot so not sure if that is the problem one).

Does somebody know where the purple wire eventually connect, PLEASE, PLEASE.
 
#11 ·
It is important to know if the wire colour is plain purple or there is any stripe on it. If there is a stripe we need colour of that stripe to be able to help.

However, if it is plain purple, then it is the wire of interior lamp in the boot (load space) which brings power from the fuse box. In this case wire thickness is 0.5 square mm. This wire is connected to other purple wires for other interior lamps (lamp under bonnet, two footwell lamps, interior unit lamp and maps lamps on the rear view mirror). All these wires thickness is 0.5 square mm.

These wires connect to centre tap point, which is under dash and from there goes thicker wire of 1.0 square mm into fuse box under steering wheel to fuse number #12. I suppose this is thicker purple wire you saw going in the fuse box?
 
#12 · (Edited)
Wiring Problem

Thanks to those who contributed earlier.

The situation at present is that I have confirmed that the only wire that appears to have been affected is the purple wire which has melted from the boot hinge to behind the dashboard at the centre console. This wire feeds the boot light and the driver and passenger footwell lights, but the wires leading to each of these 3 lights appears to be OK (no sign of melting). The purple wire to the fuse box, below and to the right side of the steering column, shows no sign of damage either.

Unfortunately, it is almost impossible to investigate further without taking the entire dashboard out. I have stripped out the centre console and the fittings below the steering wheel and under the passenger side as well. Still cant locate where the melting has extended to as we are talking about wiring that resembles a can of worms or birds nest soup. Add to that it is almost impossible to see even using a decent torch.

To save me having to remove the dash board, does anybody have a wiring loom lying about that they could check to see where the purple wire leads to. Somewhere behind the dash there must be joints/branches off the main loom which lead to the lights referred to above and the other lights referred to by Roverlike in his note above.

If you think that you can help and if I am not being clear enough, can you call me on 0141 641 2249 or 07875 159263.

Rab
 
#14 ·
Thanks to those who contributed earlier.

The situation at present is that I have confirmed that the only wire that appears to have been affected is the purple wire which has melted from the boot hinge to behind the dashboard at the centre console. This wire feeds the boot light and the driver and passenger footwell lights, but the wires leading to each of these 3 lights appears to be OK (no sign of melting). The purple wire to the fuse box, below and to the right side of the steering column, shows no sign of damage either.

Unfortunately, it is almost impossible to investigate further without taking the entire dashboard out. I have stripped out the centre console and the fittings below the steering wheel and under the passenger side as well. Still cant locate where the melting has extended to as we are talking about wiring that resembles a can of worms or birds nest soup. Add to that it is almost impossible to see even using a decent torch.

To save me having to remove the dash board, does anybody have a wiring loom lying about that they could check to see where the purple wire leads to. Somewhere behind the dash there must be joints/branches off the main loom which lead to the lights referred to above and the other lights referred to by Roverlike in his note above.

If you think that you can help and if I am not being clear enough, can you call me on 0141 641 2249 or 07875 159263.

Rab
Why not look at all the wiring diagrams that are available on the web for the MGF? I have just looked at my own set of wiring diagrams and you need to look at the diagram headed ' Power Distribution - Passenger Compartment Fusebox'. The purple wire goes to a junction box that connects to a load of kit - lamp units, analogue clock, diagnostic socket et al. ie in Google put in this search - https://www.google.ch/search?q=mgf+...sAQIHw&biw=1920&bih=903#imgrc=QeSwbr2NbW8gaM:
 
#13 · (Edited)
I do not have spare wiring from the MGF in order to help you, but I could provide some more information.

Thicker purple wire coming from the fusebox has lenght of 88.5 cm up to splice point.

Just to add what is joint together on this splice point SJ30 (P) MAIN with all purple wires:

1.0 square mm wire from fuse box, fuse #12 - 88.5 cm
0.5 square mm wires from:
- under bonnet lamp - 199 cm
- load space lamp - 484.5 cm
- front interior lamp (rear view mirror) - 214.5 cm
- diagnostic socket - 92.5 cm
- radio - 35 cm
- analogue clock - 44.5 cm
- footwell lamp LH side - 44 cm
- footwell lamp RH side - 79 cm

After seeing all these measures I see that radio has the shortes path to the splice point. Second one is LH side footwell light. So I assume that splice point should be on the LH side behined the radio.
 
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