Hello, I have a 2001 S-Type 4.0 and we were trying to track down a parasitic draw. We narrowed it down to interior fuse 20 (AC, Instruments, ECM/Front Computer). We then ruled out the AC. It appeared as though the fuses had been messed with before we got there so we tried to correct them as best as we could using online diagrams.

Now the biggest issue, is we went to start it and now we have code P1586 (ECM/Throttle) and we're in failsafe mode, which we weren't before attempting diagnostics. No throttle response whatsoever. We tried swapping the throttle relay and that did nothing. We never unplugged the ECM, nor anything in the bay other than fuses and relays. Only the fuse boxes and battery were touched between function and failsafe. Any advice is much appreciated.

 

At the front power distribution box, you're missing fuse #2. See page 20 here:

http://www.jagrepair.com/images/Auto...x2022001en.pdf


Fuse #7 should be 30A, not 20A that I see, but I don't think this would affect the engine.

 

Got that downloaded, we'll make the fuses reflect this and give it a shot on Monday. If anyone has any other suggestions to check while we're there I'm open to them.

 

I had a few minutes to dig a little deeper. Your car may not have a fuse in position #2 under the hood. The documentation does not agree. The wiring diagrams show this fuse installed in the one illustration, but I can't find what it feeds. Per the owner's manual for my '02, that position is not used. When I get a chance, I will look at my car, unless someone can beat me to it. (Stop right there, I don't mean to come look at my car, but for somebody else with an early model to look at their own car...)

Here's a quick test you can do. At the front power distribution box, place your finger on relay R4. This is the control relay for the throttle body. Have a helper cycle the key from Off to Run and back to Off. (I don't think you'll need to start the engine.) You should feel this relay click on and off. If so, that tells us power to this important relay is good and it is getting the command to open and close.

 

Thanks, I'll check for power and ground to it as well. Do you know if that relay is ground switched or live switched? If not off the top of your head, I'll dig through the diagrams.

 

The same fuse is not present on my ‘02 V6. Sorry for any confusion.

 

Update: Relay tested fine. All fuses tested fine and were made to match the manual exactly, however we're now missing a brake light. We'll address that later.

We also swapped the entire throttle body as we're fortunate enough to have a parts car. Exact same behaviour, so it's not the actuator. If I manually move the butterfly with my finger, I can make the motor rev up slowly. So the TPS circuit appears fine just the actuator circuit is iffy.

 

I see the code is about the TACM, not the TB (throttle body) - did you swap the actuator? Have you checked wiring etc?

 

The click test? Be aware that only tests the control side of the relay and the circuit to energize the internal electromagnet. It doesn't test if the relay actually sends power through the switched contacts. The easiest way to do that is substitute a known-good relay. The suspect relay (#4) is the same as the fog lamp relay (#7). Make sure the front fog lamps work and then swap the relays. See if that helps.

So a priest and a rabbi walk into a bar...

If you're going to tell jokes, so am i.

The following was industrial strength humor to help you avoid painting yourself into a corner while troubleshooting. Now I agree, the donor throttle body is not likely to have the exact same fault, but stranger things have happened. Do you know the history of the donor car? Maybe it was abandoned when the owner was told it needed an expensive replacement of the throttle body.

Or even rarer, perhaps some still undiagnosed electrical fault in your car burned up the donor part, just like the original. Don't poo-poo this idea as I have run into this several times in my line of work (aviation). After having learned this the hard way, I am always hesitant to swap complex parts between planes for troubleshooting. The ensuing conversation with the foreman never goes well, explaining how I've turned one broken plane into two.

 

I think the actuator is basically part of the throttle body. If swapping the complete throttle body assembly, this would include the actuator.

 

ZephyrWarrior, S Type Throttle Code After Drain Testing
Did you ever solve the problem?. I am living through it at the moment. Could sure use help.
Mike

 

ZephyrWarrior, S Type Throttle Code After Drain Testing

Did you ever solve the problem?. I am living through it at the moment. Could sure use help.
Mike

 

You have P1586 and no other codes?

And a 4.0?

What work have you recently done on it?

Be 100% certain your battery isn't failing - check the voltage without starting after standing overnight maybe with headlights on. What is it?

Do you have a power drain?

 

Yes to the power drain. That was my starting point , trying to find it. Between me checking fuses and relays it’s now in failsafe mode.
I was hoping that member Zephyrwarrior solved his problem. I was doing exactly what he was doing.
Battery is good.
Thanks
Mike.

 

There are threads with very detailed how to find such drains - just follow them. Search on such as quiescent current.