What is the "Auto TX fuse"?

One of the thermo fan control wires connects into it, but i don't know what it is. I suspect it resides inside the cabin of the EL, if not other models as well.

I have found out via a google search that "the auto tx fuse wiring links to the cooling fans, tranny, air bag module, ABS..".
This helps a little bit but not enough to sort me out. Does anyone have any further insight?


The thread i found the information in is reproduced below . . .

Limp mode blowing "auto tx" fuse
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Hi all!

I have an EL 97 ex-police V8 which is going into limp mode. Here's what happens;

- Cold start, drives normally for first 5-10 mins
- Blows the "auto tx" 15 amp fuse and goes into limp mode
- Engine starts to overheat (presumably coz the fuse is wired to cooling fans)
- Have to wait several hours before you can simply replace the fuse and the process repeats itself

The only exception to this is that the other day I replaced the fuse in the morning (cold start), turned the ignition and POP.. the "auto tx" fuse blows again. Today I put in a new fuse at cold start, turned the ignition and fuse remained but blew after 5 mins of driving as usual.

I notice that whenever the fuse blows, the car goes into limp mode but have no idea why. I dont think its electrical as on most occasions it takes time to blow and something tells me that if it was electrical, the fuse will blow as soon as you turn the key or start the engine.

Anyway, thinking it was low on tranny fluid I took the car straight to the transmission guys. Fluid was "very dirty" but full. They were quick to presume that the tranny was RS and were even quicker to give me a price on a total replacement!!

Later when I discussed this with an auto sparky he says it could be one of the seven solenoids..?

I know the easiest way may be to just get this looked at but was concerned that it may take "several hours" just to locate the problem - plus the cost to fix thereafter.

Before I go ahead with getting a diagnosis, is there anyone here that may know what the problem could be based on the set of circumstances outlined above? Have you heard of anything similar where something causes the "auto tx" fuse to blow?

I read about a few limp mode problems on this site but didnt really relate. I dont get any power lights flashing and no other indicators.

Thanks for helping out


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I would go to the wreckers and buy another power relay and maybe a pump relay , they are under the water filler just in front of the battery and go from there... also check the loom under the inlet manifold for a wear through where the wire go to the automatic..


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I took the car to a mechanic last week and got it plugged into a computer scan. It was connected to something in the fuse box area.

Faults appeared around the cooling fans and auto trans oil temp sensor, which we found out to be part of the wiring harness inside the tranny!

Thankfully, I had arranged an auto-sparky that morning before I went to the mechanic. It was a mobile service and he came to my house in the evening and diagnosed the problem in around 30mins and...... it had nothing to do with the cooling fans or tranny.

After all that, it turned out to be just one wire rubbing against the chassis. He simply cut the exposed wire, put in a new piece and its all fixed! Been driving it for a week with my fingers crossed and on-edge hoping nothing stuffs up but its all good.

For those of you who are interested, the auto tx fuse wiring links to the cooling fans, tranny, air bag module, ABS..

Finally, thanks to all that read this post and especially those who responded and offered their advise.

bump

On an I6 it powers the +12v side of the thermo relays, and maybe some other power for ABS, etc.

On a V8 is powers the auto computer, plus the others listed above.

Was the problem the fan wiring and not the Transmission?

I got an EL engine bay harness from a wreck, including the thermo relay block all the way to a main connector inside the cabin near the pedals. I then picked it apart to remove the thermo wiring.

The power supply for the thermo's comes directly from the alternator. The power from the alternator goes through a 60A fuse, then the relays, then the thermos. So i reckon i have this sorted.

The only thing i don't have sorted is the red wire with a green stripe that relates to the triggering of the relays. It went to the plug inside the EL's cabin and i don't know where it went from there. There are two other wires involved in the triggering, one is blue with dashs and connects relays 2 & 3 to pin 33 on the ECU. The other is blue with a white stripe and connects relay 1 to pin 53 on the ECU.

Are you saying the "auto tx fuse" powers the triggering?

If so, rather than connect the wire to the "auto tx fuse", wherever that is on my EBII (?) - if indeed it has one (?), could i power it from the +12v ignition on the ECU (pin 37 or 57) ? I have already wired it to this general area. If so, maybe adding a 15A fuse would be wise, to protect the ECU?

Its the +12v side of the control relays. The ECU does the triggering by dropping its side to ground.

Thanks, excellent.

So what do you reckon i should do?

Hang on, if i take the power from the ecu, and it goes through the relay triggers then back to the ecu, that would only make it safer, i wouldn't need a fuse? What do you think?

OK , the fans normally are powered from seperate fuses in the engine bay (40A each from memory) if you are powering them from a single 25A and that suppies the Auto as well then no wonder it blows and puts it into limp mode. Try running the relay 12V for the coil and the fan supply to a 40A Audio style inline fuse directly to the battery.

I think you've got a bit confused there. I've been on a learning curve with some of this stuff, exploring various ideas, which could make things hard for others.

My issue is how to power the trigger wires for the thermo relays. They are supposed to connect to the "auto tx fuse", but i don't know where that is on my EBII, and it's probably a bit hard to get to, and i'm thinking about alternatives.

I was thinking about using my ecu +12v (pin 37 or 57), but having already spliced my knock sensor and bbm into these i'm wondering if i might end up drawing too much power through the ecu.

So now i'm thinking i might instal a 15A fuse into the thermo relay trigger power wire, then splice it into the alternator power wire. Since these are right next to each other underneath my coolant overflow bottle, this method would be a cinch. If anyone sees a problem with this please let me know.

Too right I am confused. I think I need to re-read it from scratch.

i dont know if you got it sorted yet or not??
but the thermo fan/auto tx fuse wire can be conected to anywhere (via a fuse) where 12v ignition can be found..

i got to ask? why do you have your knock sensor conected to pin37 on your ecu???

I would wire up a fuse holder near your fuse box preferably to an ignition feed or an accessory feed no ignition would be best.As long as the thermo fans turn off while you are starting the engine.Tap into the a/c fuse the relays won't draw much current. .Kevman