TPI HELP

[John Hess]

I just read that and it didn't come out, at all, like I intended.

The caution was don't connect or disconnect to the ALDL plug while the 
ignition was on.  This can cause voltage spikes that can damage the 
ECU.  Shorting a-b and starting the engine will, indeed, place you in 
the "extended" diagnostic mode.  Sorry for the confusion.  I generally 
caution one not known to be versed in electronics to do certain things 
differently than I would instruct one who is known to be qualified.



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From:  John Hess
Sent:  Monday, March 03, 1997 10:33 AM
To:  'diy_efi at coulomb.eng.ohio-state.edu'; 
'txhartma at spdmail.spd.dsccc.com'
Subject:  RE: TPI HELP


My caution comes from advice from various sources (books by Myron
Cottrell [TPIS] and Bill Howell (Howell Engineering] and conversations 
with Don Salcido [Fuel Injection Specialties] that are much smarter in 
the area than I.  It is a caution, not a warning.  Do with it as you
like.  Generally, if you short the pins, do so before you turn on the 
ignition and disconnect while the ignition is off.

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From:
 txhartma at spdmail.spd.dsccc.com[SMTP:txhartma at spdmail.spd.dsccc.com]
Sent:  Saturday, March 01, 1997 8:57 AM
To:  diy_efi at coulomb.eng.ohio-state.edu
Subject:  Re: TPI HELP

>
> From: Scot Sealander <Sealand at clarityconnect.com>
> Subject: Re: TPI HELP
>
> John Hess wrote:
> >>> (CAUTION, do not start the engine with the pins on the ALDL
shorted).
> >> Why?  What is your concern?
> > It can (note that I did not say that it will) cause damage to the 
ECM.
>
> Can you be more specific?  What kind of damage?  Where did you learn 
> this?

I would like to know this as well - I thought that if you started
the motor with the A&B pins grounded, the ECM went into the
field-diagnostic mode and the SES/MIL would flash quickly if in
open-loop or like once per second if in closed loop.  It may also
show rich/lean or something like that right?  What am I thinking of?

thanks,

T.