John,
If the fans are running then the ecu is probably good
Pulling the 2 wire plug off the sender on the bottom of the stat housing
will have no effect on the engine rpm. You have the wrong plug and sender
I suspect.
Possibly the sender is wide open like having the plug pulled as far as the ecu is concerned.
If the fans are running the fan motors are obviously grounded.
Juice is supplied to the fan relay coils as soon as the ign is turned on
To turn on the relays the grounds to the relay coils are grounded by the heating ecu
when the temp goes above 90C or the temp sender is disconnected
Bob
- Original Message -----
From: John Driggett
To: bobbruce@mts.net ; peugeot-L@yahoogroups.com
Sent: Sunday, May 21, 2006 1:23 PM
Subject: Re: [Peugeot-L] 1991 405 Mi16 cooling system problems
Thanks for the information. I have substituted the two ecus with known good
one just because it was easy and figured it would rule two peices out. The
connector is on the sensor and when the plug is removed, the engine races to
5K RPM. I did clean both sides of the connection to be sure it was making a
good connection. I am not sure what the reading should be at the sensor. I
looked in my shop manual, but only gives information on the one for the
gauge. Also, are there any grounds related to this circuit I should be
concerned about?
>From: "Bob Bruce" <bobbruce@mts.net>
>To: <peugeot-L@yahoogroups.com>,"John" <peugeot505turbo@hotmail.com>
>Subject: Re: [Peugeot-L] 1991 405 Mi16 cooling system problems
>Date: Sun, 21 May 2006 09:45:55 -0500
>
>If the 2 wire temp sender plug is off the sender
>the temp system ecu will run the fans on high all the time
>The plug is in the bottom of the stat housing
>
>With the temp ecu tinking that the engine is over heating the ac will not
>operate
>Chech the plug clean it and put some dieelectric grease into the connector
>
>Be careful there is a wide open hole in the top of the bell housing that
>stuff can fall
>into. I lost a stat bolt down that hole and it punched out into the diff
>housing
> ----- Original Message -----
> From: John
> To: peugeot-L@yahoogroups.com
> Sent: Sunday, May 21, 2006 9:05 AM
> Subject: [Peugeot-L] 1991 405 Mi16 cooling system problems
>
>
> My 405 Mi16 now thinks it is overheating and thus the fans now run
> all the time in high, and the A/C will not operate. The temp gauge
> is in the normal range but the 'stop' light is on, and the temp
> gauge is illuminated. The oil temp gauge also reads normal, no light
> indicating low oil pressure etc. I know it is not overheating
> because it does it even when sitting overnight. I found two temp
> sensors on the side of the t-stat housing, one with a bosch style
> connector, the other with a single wire connected to it. I seem to
> remember my 405 S having a third one though, on the back of the
> head. I only see two on this car. One other side note, the heater
> flap motor was giving problems so I disconnected it, since here in
> Miami all you really need is A/C. Is it possible that another
> circuit in the climate control computer went bad and is causing
> this? I know there is a fan control box by the fuse panel but I
> think the climate control computer also ties into it.
>
> Thanks in advance for your help.
>
> John
> 89 405 S
> 91 405 S
> 91 405 Mi16
>
>
>
>
>
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Received on Sun May 21 17:59:26 2006
