TCU fuse

[paulg23]

Hi All

TCU fuse blows as soon as ignition is on. Searched forums but no luck.. Any clues of what to look for?

All the best

[Davezj]

How do you know and what were you doing before you think the fuse blew.
We don't know what you know about this issue, only what you tell us.

Sent from my MI 5s using Tapatalk

[paulg23]

I know no more. Running fine one day. Next day start up and no gear lights. Go for drive, stuck in 3rd. (limp mode). Go home check fuse and it is blown. Fit new fuse and blows as soon as ignition turned on.

[Piers1989]

Check wiring on gearbox / ECU maybe?

If the fuse is blowing sounds like a short.

[Davezj]

Right the rear lights ring a bell.
I had this issue where 3 of the 4 rear light went out and the fuse kept blowing when replaced.
Let me have a think as to why it kept blowing.
I will be back.

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[Nick Mann]

I've seen a loom shorting to the gearbox near the connectors. I'd start by whipping the air box and a couple of intake hoses off and checking the wires there.

[Davezj]

Paul, have you looked through all the fuses in the fuse box or did you just find one fuse that had blown and replaced that.
i think i remember my issue was one fuse had blown which took out the rear light then when i replaced the lights fuse there was to much current flowing through it and it blow a few time then i checked all the rest of the fuses and fond another one and replaced that and the lights fuse did not blow again. i am not 100% sure this is correct i might have done a thread on it. so i will check.

[Davezj]

can you tell us which fuse keeps blowing on the diagrams in the first post in this thread.

https://www.clubvr4.com/forum/showthread.php?46787-VR4-Fuse-Blocks-Cabin-amp-Engine-Bay&highlight=fuse+box

[Nick Mann]

I'd guess it is cabin fuse no. 3. on that list Dave. Obviously only a guess as I haven't seen the car!

[Davezj]

yes i would thought it was that one but i wanted paul to tell us exactly what he had done without too much prompting.

just in case he has done something odd.
i think there is another fuse blow that he has not checked.

i remember thinking when i fixed my issue it was a silly one and felt a bit fooling for not finding the fix sooner and wasting 6 or 7 fuses.

[paulg23]

Hi. Thanks for the responses. :)

Havnt had another chance to look at it yet. It is cabin fuse 3 that is blowing. Probably wont get to have another look till the weekend.

[Davezj]

i would suggest you check all the other fuses in the fusebox that this fuse is in and the fuses in the fusebox under the bonnet as there are more light fuses in there.

[paulg23]

Only just had a chance to get back on to this.
I have checked all other fuses that I know of... engine bay and cabin. All are OK.
I have removed all connectors from the auto box.
I have removed all connectors from the TCU (they are all blue, hope thats the right one!!!).
I have removed the reverse light bulbs (probably pointless).
Checked where I can for damaged loom.
Still blows the fuse.

Any other ideas anyone?
Anything connected to this fuse that I havnt looked at?

Its a '96 type S with AYC, TCL and ASC.

[Nick Mann]

Could it be the loom from the fusebox to the tcu? An alarm at the bacm of the fusebox or a radio above the tcu?

[paulg23]

Could it be the loom from the fusebox to the tcu? An alarm at the bacm of the fusebox or a radio above the tcu?

I'll have a look. Thanks.

[paulg23]

Stumped!!! Bet it's something stupid when/if I find it. Anyone point me to a wiring diagram that covers this?

[Nick Mann]

http://www.clubvr4.com/forum/showthread.php?5507-Galant-Workshop-Manual-PDF-s-x-26

But the chassis electrical seems to think the auto transmission is covered in the auto transmission chapter - that only covers the pins on the TCU.

[paulg23]

As previously said, tried everything to no avail. So left it. Everything that uses that fuse disconnected. All pipe work above gearbox removed. All lower dash removed. All center console removed. Didn't find anything. Today fuse not blowing. Replaced all connectors, replaced all under bonnet pipework and drives like a dream!!!!!!!!!!!!!

Now got to rebuild the interior.

Power steering pump leaking.... anyone know if it is used by other vehicles?

[Nick Mann]

I think it's the same on similar aged V6 models. It could be common with the FTO? I'm sure it changed from pre to post facelift though.