Another slow down light question

1-4 slow down light sometimes stays on when the ignition is on,and stays on when the engine is started,5-8 goes out.
Doesn't do it all the time.
Also pulled the ECU covers to check the codes,where is the button.There is a a plug with 3 wires next to each ECU which has a cover on it.

 

You want to check the resistance between the #1 pin and #6 pin under each MAF cable (but on the MAF male pins). Both MAFs should have the same value (factory preset at 383 ohms, for reference). The cheapest ohmeter will do fine. Engine off for measurement.

Then you'll want to swap the left exhaust ecu with the right exhaust ecu to see if your slow down lights reverse (i.e. 5-8 staying on instead of going out). The answer (yes, lights reverse, or no, lights stay the same) will impact how you then procede.

As for your codes, Euro cars may require a dealer tool to check...also, the codes are related to the Check Engine Lights rather than to the Slow Down lights.

 

Folks might be more forthcoming if you would tell us what model you are asking about!!

 

sorry 348 GTS

 

Just swapped the ECU's and 5/8 stays on and 1/4 now goes out.I presume it's a a new ECU or can they be repaired?

RE: the CEL's,I was just going to check the codes out of interest

 

Well I hate to break the news to you but, you don't have the self diagnosis button in your car. The reason is because they only came on U.S. cars. It was a federal requirement at the time. Euro cars are not equiped with the button. Sorry bro.

But the good thing is that you found the bad ecu. If you are NOT running catayltic converters (using test pipes) to can just unplug it. If you are running cats, then just get a new one.

 

NO bad news mate,I just found it confusing that all the info I could find about pulling the codes refered to the buttons.Found out that the button and a small harness that plugs into the capped plug is listed.

Still got the cats.I can start the car with the 1/4 light on with no power loss,what do you make of that?

 

Steve have not owned a Euro car so this thought is only based on what I know and what you have described. You said that there is a 3 wire plug next to each ECU correct? this may be the same wire/plug that we have here in the US but we have a button plugged into it. I am wondering if you could attach the US version button to this and read your codes on your car as we can do here in the US. You do have check engine lights on you dash don't you? The button we have mainly just opens the OBD circut and flashes fault codes, via the dash lights, related to the sensors and engine ECUs. Regards, Vern

 

Right, it's the exhaust ecu. Good troubleshooting, mate!

I haven't opened one up to see if they can be repaired, but I've got a spare that I may have to crack into now to see.

As for checking the a/f codes, several fchatters have recently been posting that they have the 3 wire cable, but no button plugged in, so if you have a part number for the button/cable, post it!

 

Yeah,I think your right Vern,looks like you boys over there got the button and we didn't.It is listed as a seperate part though.

 

Yeah I noticed the same on the part no. shows for NA only. One of the good things our government has done for us, all cars have to have it in the US.

 

tester cable 146196
button 145810

 

Too spoilt you boys i tell ya....

 

Anybody got any thoughts as to why the light is on and there is no power loss

 

Do you mean the slow down light or the CEL?

 

slow down light 1/4

Turn ignition on(engine not running)warning lights on inc abs,slow down 1/4 and 5/8.After a couple of seconds 5/8 goes out but 1/4 stays on.Start engine 1/4 slow down light still on but engine runs OK.
Swapped exhaust ECU's round and 5/8 stays on,indicating a problem with the exhaust ECU.I thought that if one of the slow down lights was on then one bank should be shut down and you would notice the power loss.

 

Sometimes they shut down the injectors sometimes not. It's just a malfunctioing ECU turns on the light but not shutting off injectors. That's all it was designed to do, shut off injectors when it "thinks" the cat is too hot. These things are notorious for doing this. My car would turn on the light and shut off the injection on the offending bank even when the cats were not hot.

 

That makes sense,getting a better understanding of how this system works now(still prefer points and carbs )Cheers Vern.

 

LOL. carbs and pionts? Once you get used to how the Motronics work they really are a great way to produce good HP and clean air with respectable fuel milage. When you think about this little motor producing 300 hp, in your case 320 it's fantastic and all do to the technology of electronic engine management. Regards, Vern

 

The Slow Down light has to stay on for more than 5 minutes before a bank will be shut down (presuming things work as in the book).

Not sure how you'd go about repairing one of the exhaust ecus...

My spare exhaust ecu appears sealed tight with no screws or bolts to undo to open it up.
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Yep, epoxy "potted." No user serviceable parts inside!

 

Now that answers a question,this has happened before,previously if I have shut the engine off and restarted the light has either gone off straight away or after a couple of minutes.I originaly put it down to a poor connection but have since done the stabilant thing and reset the ECU's after doing it's annual service.Thought I'd sorted it until earlier,now I wonder if the light will go out after a short while.
Or do you think this exhuast ECU is coming to the end of it's life.

 

Take out the ECU and look at it carefully. Are the edges of the epoxy cracked where it meets the casing? If so, I think you're on borrowed time. Peter, do you concur?

 

I think that it's widely accepted that the 348 exhaust ecus eventually get a crack in the epoxy that allows moisture to enter, and once entered, the problems only grow over time with any particular exhaust ecu.

That being said, there would seem to be very little downside to carving out the epoxy with a blade of some sort to see if you can spot obvious corrosion or broken connections inside...at least, if your exhaust ecu has already failed.

I mean, you're going to replace it anyway (unless your surgery saves it).

 

Just thinking out loud, but you might spray WD-40 into any exhaust ecu cracks...WD-40 = Water Displacement version 40...sort of designedf for this type of repair...