[Wi RoZ]

The engine on my '04 TF 160 is running rough and now and then P1521 pops up (VVC actuator #1 faulty).

So I decided to check the wiring and was a little dumbfounded when I saw that the ground wires of all injectors, the EVAP system, the CMP, the VVC actuators and some other stuff have a stable 2 Volts on them with the ignition ON 🤔. The supply is a healthy 5V or 11.8V, but the potential difference over most of the aformentioned stuff is now 9.8V.

The CMP (camshaft position sensor) is even more weird. Measured on the plug (disconnected from the CMP) with the ignition ON, the signal wire has about 2.5V and the ground wire has about 1.5V

I suspect a short of some sort somewhere. But before I take the whole loom apart or create a break out box for the ECU, I decided to post here first.

Does anybody recognize this problem and/or knows any problematic parts of connectors or the wiring harness?

Thanks in advance

EDIT

I will post the solution when the problem is fixed

 

[Roverlike]

First thing I would suggest is to check if you have some broken wires at boot hinge folding area: MG F/TF Boot Hinge/Lid Wiring Loom Inspection Guide since earth point which correspond with those wires which might break and touching each other is also erthing point of engine ecu

 

[EllisoJo]

I was about to post suggesting boot hinge wires, but saw that Roverlike got there first.

First thing I would suggest is to check if you have some broken wires at boot hinge folding area:

These wires are NOTORIOUS for failing in a hard-to-access area where they flex.

 

[Wi RoZ]

First thing I would suggest is to check if you have some broken wires at boot hinge folding area: MG F/TF Boot Hinge/Lid Wiring Loom Inspection Guide since earth point which correspond with those wires which might break and touching each other is also erthing point of engine ecu

I was about to post suggesting boot hinge wires, but saw that Roverlike got there first.


These wires are NOTORIOUS for failing in a hard-to-access area where they flex.

Thx, I'll check 'm today

 

[Chris T]

If the boot loom looks to be OK another place to check for damaged wires is behind the radio, the wires can become trapped against sharp bodywork that sit directly behind the radio.

 

[D4KGP]

I was about to post suggesting boot hinge wires, but saw that Roverlike got there first.


These wires are NOTORIOUS for failing in a hard-to-access area where they flex.

I don't think they are hard to access, I didn't find the job hard to do when I done mine. Regards. D4KGP.

 

[Wi RoZ]

Thx for the replies guys 🙂

I just checked the boot loom, and there were 2 wires that were slightly damaged but weren't touching each other. One of them is a ground wire that was half split, I just fixed that. Also taped them individually with electro-tape. Doesn't make a difference 🙁

As for the radio, I repaired those cables last year when I installed a new head unit and put some protection on the sharp edges.

On the upside, at least I fixed something today 😋

More ideas are welcome 🙂

EDIT

Just found a loose cable when I was fumbling around the split joint of the boot loom into the main harness. Also the IAVC started ticking when I was moving around there.

If the weather permits I'll proceed tomorrow. Otherwise it's gonna be Saturday. I think I'm searching in the right spot.

Have a good one guys 🙂

 

[Wi RoZ]

UPDATE

So today I had some time to do more work on the TF. Disconnected the negative on the battery first, then took out the ECU and its bracket. Proceeded with cutting open the tape around the main wiring harness on the left side of the ECU to check if there where any more damaged wires.

TIP: when splicing protective tape on a loom, use a seam ripper. It won't damage the wiring and cuts the tape real easy. Use the dull end on the inside for obvious reasons.

Lo and behold, there was another damaged ground wire. This time cleft in twine. When I started looking for the other half I found out that some miscreant apparently took that other half, put a lug on it and bolted it to the chassis, leaving the first half unconnected. Whether or not it makes any difference I'm not sure yet, but I guess I'll find out tomorrow.

Also I found the other half of an aformentioned loose wire, soldered them together and wrapped some tape around.

I'll update again tomorrow if I made any progress. Cheers 🍻

 

[Wi RoZ]

UPDATE 2

After checking some more loom and fixing the broken wires, the problem still persists. Apparently one of the broken wires was from the open boot warning light, which now works.

I still have a steady 1.98V on the ground pins of all injector plugs, the EVAP cannister plug and some other stuff. No clue.

Because it's still so steady after messing around with the wiring harness, I suspect something might be wired incorrectly. But I can't properly measure that unless I make a sort of breakout cable that I can place in between the ECU plugs and connectors. That way I can measure voltage on the ECU pins while it's plugged in. Problem is finding the right plugs and connectors to make such a cable

Does anybody have more ideas? 🤔 They're more than welcome.

 

[Roverlike]

Way to make a check is to take the plug and one end of multimeter terminal to earth pin and with other terminal check each other pins to see if you have connectivity. This way you ight find which wire or pin produces this error. It is possible that some small piece of loose wire is touching another pin on connector itself.

 

[pisxa]

Unplug the negative battery connector and try to clean and sand it, it helped me when I had voltage drops in my 135 TF.

 

[Wi RoZ]

Way to make a check is to take the plug and one end of multimeter terminal to earth pin and with other terminal check each other pins to see if you have connectivity. This way you ight find which wire or pin produces this error. It is possible that some small piece of loose wire is touching another pin on connector itself.

I've already done that, but I'll try again tomorrow. Maybe I missed something. Thx for the reply 🙂

EDIT

I just remembered that the ECU has to power some wires. With the ECU disconnected does wires aren't powered and are not measurable, so the problem might not exist then.

 

[Wi RoZ]

Unplug the negative battery connector and try to clean and sand it, it helped me when I had voltage drops in my 135 TF.

I'll do that as well. If I take a random chassis point as ground I get a perfect 11.8 V. Heck, even the throttle spring gives me 11.8 V as a ground point. But that is low load.

Thx 👍

 

[Wi RoZ]

Haven't had the time to fix the problem yet, but I suspect this:

It is possible that some small piece of loose wire is touching another pin on connector itself.

Will try and fix it after the weekend. And if I manage to fix it I will upload a little how-to. I'll also post a how-to for making a little break-out box for the MEMS3 ECU.

 

[Wi RoZ]

Still haven't had the time to look into it. I'm going to check some other things tonight though.