Re: [doc] Spare Idle ECU

[Martin Gutkowski <martin@xxxxxxxxxxxxxx>]

Much easier to check the ECU first.... Daniel, I'll be back in Kent with 
my D this weekend after the Thatcham trip, I can pop over Sunday and 
we'll try my ecu in your car

FYI Nick, we've troubleshooted (is that a word?) approximately 8 high 
idle problems since DMUK started, and of those, 4 had faulty ECU's, 
sometimes in addition to other problems. Only seen one idlespeed motor 
failed, but the most common cause by a long way is the idlespeed 
thermistor being either failed or disconnected. This can be checked 
across pins 9 and 11 of the ECU. If it's open circuit, it's the problem 
(though may be wirign and not the sensor itself).

It was Phil's that caused the most head-scratching!

Best Wishes

Martin

Nick Tomlinson wrote:

> Hi Daniel,
>
> I'm a control system programming engineer (for my sins) and the number 
> of times the Programmable Logic Controller [PLC] (black box!) is 
> blamed for production/ process faults is unbelievable. Most of the 
> times they are not the fault but wires and/ or instrumentation 
> (sensors). Same applies for cars. As long as the basics have been 
> checked first.
>
> Checking the idle speed motor valve...
>
> Remove valve. Spray carb cleaner in it, shake it, spray wd40 in it. 
> shake it. Pour out excessive wd40.
>
> On a test bench, use a multimeter and then measure the resistance from 
> the middle pin to one of the outer pins. Should be in range 5-20 ohms 
> of 150-250 ohms (depending on model). Now repeat for middle pin and 
> other outer pin. Should be near same result as for first.
>
> Now, carefully touch from a car battery 12v to the centre pin then 
> MOMENTARILY connect the 0v (earth) connection to one of the outer 
> pins. This should either fully open or fully close the valve. It will 
> shake as you do it. Test by blowing through the valve with your mouth 
> in the direction on the arrow stamped on the side of the valve. Do the 
> same test and the valve should go in the opposite direction.
>
> If the valve doesn't move then it is probably seized. If it is then 
> chuck it in the bin and buy a new one. I'm sure Martin has some and 
> I'm presuming you live near him (down saaaaaarrff guv'nor). I live up 
> north about an hours drive from ChrisP's
>
> Also, with the ignition on position 2 and the idle speed ecu connected 
> you should get 12v on the centre plug. If you don't check the fuse #1 
> (if my memory serves me right) and the voltage to the ecu (see 
> workshop manual). If you DO get 12v to the ecu but not 12v at the plug 
> then it is either the wiring OR a diode has gone open circuit on the 
> ECU. If this is the case then a diode can be connected externally as a 
> temporary test.
>
> Good luck.
>
> Nick.





DOC UK Website: www.deloreans.co.uk
Unsubscribe: doc-uk-unsubscribe@xxxxxxxxxxxxxxx
** Unless otherwise stated, all messages posted to the group are assumed public and may be printed in the club magazine **

Yahoo! Groups Sponsor

ADVERTISEMENT

---

Yahoo! Groups Links

• To visit your group on the web, go to:
  http://groups.yahoo.com/group/doc-uk/
   
• To unsubscribe from this group, send an email to:
  doc-uk-unsubscribe@xxxxxxxxxxxxxxx
   
• Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.