No ECU light in service mode

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No ECU light in service mode

Postby Chas54 » Wed 13.10.2021, 19:12

During the course my recent Injector swap ive done something to the service mode circuit i think.
I got locked out by the immobilzer for a few days , but now i have the engine running again, i find that when i use my dapinky switch the engine tone changes and hunts up and down , but the ECU light doesnt come on at all. It is on when the ignition switch is first turned though.

If anyone has any ideas i would be greatfull

Cgarlie
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Re: No ECU light in service mode

Postby Simon_P » Wed 13.10.2021, 22:06

Check that the ECU plug is correctly seated.

If you still have a problem check the pin voltages in line with the EMK /EMJ manual - pages 86 and 99 come to mind.
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Re: No ECU light in service mode

Postby Chas54 » Thu 14.10.2021, 19:19

Simon

I unplugged the ECU and then re plugged it , i thought intially all was good as the ECU light on the dashboard was flashing in the service mode although the car was still hunting up and down . It wouldnt idle in normal operation though, warming had to be done with the throttle part open.
After running and trying to adjust the idle air screw, the system recorded 40000 faults - I'm guessing thats the maximum it will store.


I cleared these with a battery dissconnect, got locked out by the immoblizer again , and now when starting i get one pulse light on the ECU and also when selecting service mode i just get one blink of the light then it stays off. It has entered service mode though as i can see the IAC goes to 20 counts and the pulsating revs start..

I will check the voltage at the pins as you suggested, i think it should be 5V looking at the manual .

Also if all else fails ,i may put the old ECU back and revert to open loop . I have not tried these new ebay injectors like that yet . I'm wondering if i have a problem with injector wiring as i have disturbed it all moving it out the way when messing about with the injectors. The wiring probably suffers from the heat in the area as i think it may be brittle.

I have planned to take the immobilser off this Sunday, I have an assistant to help ring through the cables, may get the injector wiring chased at the same time.
Incidentally , its not a plug as I have pulled each lead in turn and have a corresponding drop in revs for each.


Thanks for suggestions

Charlie
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Re: No ECU light in service mode

Postby Simon_P » Thu 14.10.2021, 20:26

Charlie,
There are lots of pins and a specific voltage for each. There are two tables for engine running /not.
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Re: No ECU light in service mode

Postby Chas54 » Fri 15.10.2021, 08:40

Thanks Simon.

I've found that, the only thing I am not sure of is if the stated voltage is plugged in or can I measure the plug pin, unplugged.
If it has to be plugged in it's a little crowded to get probe into the conductors.
Charlie
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Re: No ECU light in service mode

Postby Chas54 » Fri 15.10.2021, 11:04

Sorry Simon

My last post a bit daft really. Now i've printed and read the plug pin chart its pretty obvious it has to be plugged in.

Just got to find something i can poke into the cable housing at the plug .


Charlie
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Re: No ECU light in service mode

Postby Chas54 » Fri 15.10.2021, 16:34

Not quite so easy without having the ECU on jumpers . I found it virtually impossible to tell which cable i was probing . I tried a thin piece of fuse wire .

I can't see what i'm doing at the rear of the cable plugs . I can only think puncturing the insulation would allow probing but i don't like that idea much.

I took the coils off and cleaned them as i thought i may have lost some water there when tipping up the header tank to move it out the way, but no difference made . I briefly swapped back to the original ECU and set the CO pot to its mid range resistance position - still running to rough so I dont think its the new closed loop system.

But here's a funny thing i've tried. I know the vacuum on the plenum is going up and down with the engine revs ( as i most likely would) so i thought i'd use my vacuum hand pump on the MAP to set a constant vacuum. Then with a vacuum gauge connected directly to the MAP tapping point on the plenum start the engine and noted this:- The engine runs sweet and steady , the actual plenum vacuum is steady ( somewhere around 500mm Hg) . If i improve the vacuum with the hand pump the engine runs rough then cuts out at around the same vacuum.

I tried this with the petrol reg valve vacuum connection blanked off as well, so as to prove the reg isn't dumping petrol to early. It still cuts out. I have to suspect the MAP sensor but i changed it less than two years ago. I also know that on the open loop system it didn't do this.

I thing my next point is to check the voltages at the MAP under varied vacuum.

any comments appreciated

Charlie
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Re: No ECU light in service mode

Postby Simon_P » Fri 15.10.2021, 20:42

You can remove the blue bits for better access to the bank of the pins.
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Re: No ECU light in service mode

Postby Chas54 » Sat 16.10.2021, 16:56

Simon.
Thanks for tip . its loads easier with the blue and grey pulling aids removed, I hadn't realised they came unclipped so easily.

Short piece of fuse wire held in the meters croc clip down each cable side seems to work.

Despite my earlier concern about the MAP, it seems to work as it should . with it blanked off and on the running car i could get to about 400mm Hg vacuum(0.5bar) at which point the engine stops . The voltages at the ECU pins check out Ok though . The engine runs really smooth until i reconnect everything.
The current state is its running a bit rough , but with a good vacuum about 0.35 bar .

I still dont get the flashing ECU light on the dash when entering service mode . Although i get the 12 code initially indicating entering the service mode if i have the engine stopped but ignition on.
I have no stored faults now .

I may get time tomorrow to check the rest of the pins on a warm running engine .

One thing that surprised me when looking for an earth to use on the other meter cable was that the ECU case is not connected to the earthing pins on the ECU terminals.

Thanks for advice

charlie
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Re: No ECU light in service mode

Postby Simon_P » Sun 17.10.2021, 21:59

Do you have the ECU out of the bracket in the footwell?

I think that the case is for shielding, so connecting it to the ECU ground might be counterproductive.

How do your pin voltages compare to the maual?
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