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        General >> Problems >> Overdrive not engaging
        
(Message started by: Jim on Jan 24^th, 2005, 8:50pm)

Title: Overdrive not engaging
Post by Jim on Jan 24^th, 2005, 8:50pm

2.3 auto giving much head scratching. ???
The overdrive does not appear to be engaging. Turning it on & off brings light on but no reaction from gearbox. During deceleration the overdrive seems to work and can be turned on & off giving additional breaking from the engine. There are no dtc's, oil levels ok, the maf has been cleaned and the gearbox operates without trouble. Incidently what would be the reduction in revs when overdrive is in operation?

Title: Re: Overdrive not engaging
Post by waders on Jan 24^th, 2005, 10:02pm

Jim,

Sure you got a problem? O/Drive (4th gear) wont engage below about 50 mph weather you swich it off and back on again or not. If it was the MAF or a solenoid failing you should expect a flashing O/D light. Try to find o/drive kicking in around 50ish.

HTH

8) ;D 8) ;D 8)

Title: Re: Overdrive not engaging
Post by gadgetmandb on Jan 25^th, 2005, 1:13pm

My Overdrive will work at 30 mph.

R Reg 2.4 Auto Scorpio

Title: Re: Overdrive not engaging
Post by Jim on Jan 25^th, 2005, 2:04pm

I've tried it all the way up to 90 but no overdrive. No flashing od lights. ODB readings don't show any errors. What would I expect the torque converter readings to show?

Title: Re: Overdrive not engaging
Post by desperate on Jan 25^th, 2005, 2:06pm

My od kicks in at 55mph and the rev drop is about 500rpm's.

Is the actual switch ok ??

Title: Re: Overdrive not engaging
Post by Eddie on Jan 25^th, 2005, 3:26pm

A 2.4 Scorpio? Is this just a typo?

eddie

Title: Re: Overdrive not engaging
Post by Vulcan on Jan 25^th, 2005, 5:28pm

on 01/25/05 at 13:13:22, gadgetmandb wrote:

My Overdrive will work at 30 mph.

R Reg 2.4 Auto Scorpio

No matter how I try I can't get my o/d to operate before I reach about 50mph.... ???

Title: Re: Overdrive not engaging
Post by ren on Jan 25^th, 2005, 9:05pm

Vulcan
His is a 2.4 ? yours is a 2.9
my cruise can operate around 30mph
overdrive dont kick in till about 48/49mph

Ren

Title: Re: Overdrive not engaging
Post by ren on Jan 26^th, 2005, 7:32pm

Jim
have u sussed the o/d problem
u had.

Ren

Title: Re: Overdrive not engaging
Post by Jim on Jan 26^th, 2005, 10:44pm

Afraid not, still scratching head ???

Title: Re: Overdrive not engaging
Post by desperate on Jan 26^th, 2005, 10:47pm

Jim,

Have you done one of them OBD thing scans ??

Title: Re: Overdrive not engaging
Post by Jim on Jan 26^th, 2005, 10:58pm

Yes, obd in place during a 20 mile run, didn't show any dtc's and all readings showed no obviouse errors. However, I do not understand all the readings that are given. :o

Title: Re: Overdrive not engaging
Post by ren on Jan 27^th, 2005, 7:26pm

Jim
as per owners handbook, and as the info on the
main page explains why, type o/d in the search box.
D=Drive (driving with overdrive)
The normal driving posistion,all 4 gears are selected.
D=Drive (driving without overdrive)
The overdrive function can be switched off,by pressing
the locking button on the side of the selector lever,
the corresponding control light in the instrument panel
will illuminate.
the transmission will now select only gears 1 to 3.

Hth
Ren

Title: Re: Overdrive not engaging
Post by Jim on Jan 27^th, 2005, 11:09pm

Its getting deeper into the tech stuff. I have been giving the odb readout a good looking at and going through at low readback speed. Checking VSS against RPM and GEAR. odb shows gear change from 3rd to 4th at VSS of 50. No drop in rpm it stays at 2500. It looks like the management system commands the gear change and ideed sees it but the gearbox doesn't actualy change. This is the feeling when you drive, that is no change up and no drop in rev counter. More suggestions please.

Title: Re: Overdrive not engaging
Post by ren on Jan 28^th, 2005, 3:52am

Have you tried turning o/d off just after
starting car so you only have gears 1 to 3
run it up to 65/70 then put o/d on (4th gear)
would think that will give a significant rpm reduction

have you tried it in both economy and sports mode

Title: Re: Overdrive not engaging
Post by scorpio_man on Jan 28^th, 2005, 11:36am

hi there

the only other thing i can think off is the Brake On Off(BOO) switch. if this is stuck on, then the torque converter won't engage. i'm not sure what effect this will have or if a code is registered, but it's something else to check.

hth

Title: Re: Overdrive not engaging
Post by waders on Jan 28^th, 2005, 7:27pm

Jim,

Where are you in our green and pleasent land? Anywhere near Barnet or the M25?

waders.

Title: Re: Overdrive not engaging
Post by Jim on Feb 4^th, 2005, 6:59pm

Sorry for the delay but only just got my broadband back, Ntl are a bit like scorpios, briliant whilst it works.
Tried last suggestion no different, live in Dagenham and just seen a posting entitled 'lost 4th gear' sounds similar.

Title: Re: Overdrive not engaging
Post by waders on Feb 4^th, 2005, 7:38pm

I'm less than half hour away (unless it's rush hour :-/)

Send me a PM if you want to come my way 8) for some OBD ;)

Barry.

Title: Re: Overdrive not engaging
Post by gaz01gaz on Feb 4^th, 2005, 10:29pm

jim, i have all the same symptons???? exactly as you describe,unfortunately there does't seem to be any one around me in yorks available to do the fault scan,i am at a dead end,under acceleration i cannot get 4th gear as soon as i lift off or begin coasting it changes as you see the revs drop slightly and if you hit the o/d button you feel it change down and up ???not sure all this helps you but lets you know your'e not on your own out there!!!!gaz

Title: Re: Overdrive not engaging
Post by Eric_R on Feb 6^th, 2005, 4:54pm

Jim & Gaz,
There are several issues here that we need to consider,
Firstly, standard OBD codes only report malfunctions connected with emissions, so gearbox malfunctions are reported on a different CODES page, the Enhanced codes - see http://www.fordscorpio.co.uk/easyguide.htm to make sure you read both standard and Enhanced (Ford only) codes, otherwise you'll miss most of the Comprehensive Components Monitor diagnostics. Once you're there you'll probably find DTCs in the range 1700 onwards - normally P1733 and/or P1761.

Secondly, the Overdrive name is a bit of a misnomer - actually it is simply a fourth gear, but called Overdrive for historical reasons where additional sun/planet drives were fitted to the back of gearboxes to give more relaxed engine revs at cruising speeds - now this sun/planet drive has been moved inside the gearbox to create fourth gear. The green button marked O/D simply deactivates the selection of 4th until it is pressed again.

Thirdly, RPM can rise and fall regardless of gear selection because of the TCC - Torque Converter Clutch. This locks up the Torque Converter at lower throttle openings to reduce RPM and save fuel, but it releases smoothly depending on torque demand. In this way you can press on the accelerator at cruising speed and the revs can rise smoothly even when the autobox is still in fourth.

However, if you're at 60-70mph and you click off the OD button you should certainly see the RPM rise by 300-450 rpm, depending on engine, and if you don't then 4th is not engaging - and if it isn't then there must be a DTC recorded in the Enhanced Codes diagnostics.

HTH

Title: Re: Overdrive not engaging
Post by Jim on Feb 10^th, 2005, 3:22am

Eric_R
Have been looking at the odb readings again. No dtc's, but no drop in revs. ODB readings show it is in 4th gear. What if the problem is with the torque converter? Is that isolated from the management system?