auto trans and idling issues.
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Elder User
Joined: Nov 2004
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auto trans and idling issues.
last night i helped a friend buy a 99 250 4x4 auto. build date is 6/99.
when driving it you can hear the usuall ford ps pump whine, i think the pressure is low cause if you are on the brake and try to turn the wheal it is very stiff, but only when using the brake. wich brings me to my first question, when sitting at a stop light for a little while the rpms start to drop to around 450-500 then back up to around 800 or 900, then back down. it would only do this IN GEAR, NOT NEUTRAL OR PARK, and only with your foot on the brake. i ran a KOER test and get a trans code for p1746 "pressure control selenoid circuit open" (does shift hard). could the idle issue be from the trans, or maybe the low ps pressure? (or not related to either?)
the other codes that come up are
p0605 pcm internal rom error (mine does the same every test but nothing when driven)
p0470 exhaust pressure sensor circuit fault.(not too concernd about that right now, tube looks rusted)
any suggestions on this "pressure control solenoid", how hard to fix? and could this in any way be tied to the idle issue?
when driving it you can hear the usuall ford ps pump whine, i think the pressure is low cause if you are on the brake and try to turn the wheal it is very stiff, but only when using the brake. wich brings me to my first question, when sitting at a stop light for a little while the rpms start to drop to around 450-500 then back up to around 800 or 900, then back down. it would only do this IN GEAR, NOT NEUTRAL OR PARK, and only with your foot on the brake. i ran a KOER test and get a trans code for p1746 "pressure control selenoid circuit open" (does shift hard). could the idle issue be from the trans, or maybe the low ps pressure? (or not related to either?)
the other codes that come up are
p0605 pcm internal rom error (mine does the same every test but nothing when driven)
p0470 exhaust pressure sensor circuit fault.(not too concernd about that right now, tube looks rusted)
any suggestions on this "pressure control solenoid", how hard to fix? and could this in any way be tied to the idle issue?
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,717
Likes: 2,643
From: SE Florida
Find and fix the open or short circuit to the Electronic Pressure Control (EPC) solenoid. That is making the line pressure be at max, and the pump can't handle that at idle speed. Your idle issues will go away once this is fixed. It could be the wiring to the solenoid or a bad solenoid.
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