[Supras] Factory shielding of knock sensors

[Walker, Brian (Rich. Dist)]

Bernie, I never noticed the factory shielding being grounded at all
(88T) which is why, when replaced, we grounded it near the ecu. It
doesn't make a lot of sense to run the ground so far either, aren't the
KS's on the intake side, opposite the AFM? That's a lot of extra wiring
to run and like mentioned, I didn't noticed them being grounded when
removed. One sensor fell apart when disconnecting the wire, never showed
codes though (I'm thinking it and the wiring was the source of the
wildly varying power)
Perhaps Toyota realized at some point shielding works much better when
grounded?
Brian

Date: Mon, 23 Jul 2007 00:16:14 -0400
From: "berniek at technicaldevelop.com" <berniek at technicaldevelop.com>
Subject: [Supras] Factory shielding of knock sensors
To: "Supras at supras.com" <Supras at supras.com>,	berniek
	<berniek at technicaldevelop.com>
Message-ID: <46A42B8E.1050405 at technicaldevelop.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

The '91-up manual set I have here shows the knock sensor cabling to be 
shielded in much the same manner as mods which have been posted on this 
same group.  I inspected the forward most sensor wire and found it to be

shielded about 2" back from where the overall protective tubing starts 
at the sensor.  According the the wiring schematic, the shields are 
grounded to a common point near the AFM ground.  However, I have seen 
mods involving shield grounding at both the block and the ECU case (with

soldering to the ECU case whch can be done to aluminum with SAL-Met flux

with difficulty).  So the factory shield grounding point does not seem 
that outrageous.  Yet I had instances with my '90 where knock sensor 
codes were set.  I have a brand new '90 harness in the original plastic 
bag (which will be for sale) which shows the same shielding.  Maybe it 
was an upgrade from the original. since I did have knock codes set a 
couple of times on the '90 before the BHG.  There were no codes set on 
the '90 when it was received from the dealer. 

Were the list modification comments intended for older harnesses only?  
Both the 91 and '90 manuals show the shielding (referred to as 
sealing").  Any comments would be appreciated.  Thanks.

       BernieK