[mkiv] Codes 42, 71, and 89 simultaneously on hot days... wth???

Sun Sep 13 14:53:57 CDT 2009

Hey John,

Totally O.T. question...
Were you at TX2K9 back in March? 

This car has had issues with the EGR since before I bought it although they're much better now that it doesn't have completely fubar smoking twins on it anymore.  The EGR parts are still bolted to the head but the vacuum lines are all disconnected and the sensor connector's been resistor'd which helped immensely but didn't solve it. 

I'm wondering if all the crap which included both oil and coolant that was getting past the bad turbo's shaft seal into both the intake and the exhaust has just clogged up the EGR system and coated and upset its' temp sensor.  I've put close to 7k miles on it since the fubar factory turbos were replaced and it doesn't smoke at all anymore so I'm not sure... 

I'm not having any issues with the manu button and indicator other than once the three codes are tripped including the 89, the manu and trac off buttons don't change the state of their indicator lamps 'till the codes decide to clear or I reset the ecu.

Thomas

--- On Sun, 9/13/09, John Cribb <johnacribb at yahoo.com> wrote:
From: John Cribb <johnacribb at yahoo.com>
Subject: Re: [mkiv] Codes 42, 71, and 89 simultaneously on hot days... wth???
To: "The MKIV.com National Mailing List" <mkiv at mkiv.com>
Date: Sunday, September 13, 2009, 8:43 AM

Thomas, I didn't have the MIL from the EGR (71) until after I put the EGR bypass plate in, and then it only occurred infrequently, in hot weather, and only when cruising between 30 & 50 MPH. I've disabled the rest of the EGR, put the resistor in, replaced the resistor twice, cut the harness and soldered the resistor in, etc. but no joy.

The other problems that you're describing, (TRAC Off, Manu, Cruise) I had when I first purchased my car, but they all were sorted when I resoldered all the points in my instrument cluster.

My '94 is now owned & driven by my son, but it's still tripping the 71 MIL occasionally, so I'm still keen to find a solution.

John
'97 RSP 6spd APU hardtop

--- On Sun, 9/13/09, Thomas Bradley <myothersupra at yahoo.com> wrote:

> From: Thomas Bradley <myothersupra at yahoo.com>
> Subject: Re: [mkiv] Codes 42, 71, and 89 simultaneously on hot days...  wth???
> To: "The MKIV.com National Mailing List" <mkiv at mkiv.com>
> Date: Sunday, September 13, 2009, 5:17 AM
> Hey John, 
> Sounds like your 94TT auto had the same issue I've got with
> this 93TT auto (Code 71) and that you did the same things to
> try and solve it, which helped some but didn't solve it... 
>  
> Anyone have any insight into what we're missing about this
> issue? 
>  
> Already did that tech tip (both sides) shortly after I
> bought the car.  I'm very familiar with it. 
> It didn't solve the problems, just made them apparent as
> most of the warning lamps in the left and right
> warning pods and instrument cluster itself didn't work
> when I bought the car...  no suprise there with 120k miles
> on a bone stock TT Supra... 
>  
> The odo resolder fixed the cruise completely and helped the
> code 42 go from constant to only showing up when the other
> 2 codes show up, 42, 71, 89, all simultaneously. 
>  
> w.t.h...
>  
> Thomas
>  
> --- On Sun, 9/13/09, John Cribb <johnacribb at yahoo.com>
> wrote:
> 
> From: John Cribb <johnacribb at yahoo.com>
> Subject: Re: [mkiv] Codes 42, 71, and 89 simultaneously on
> hot days... wth???
> To: "The MKIV.com National Mailing List" <mkiv at mkiv.com>
> Date: Sunday, September 13, 2009, 12:57 AM
> 
> Thomas you might still have a cold solder joint problem in
> the instrument cluster. If I were you, I would resolder all
> the joints in the cluster, not just the odo pod. http://www.mkiv.com/techarticles/trac_off_mil_odo/index.html
> 
> Also I'm not clear if the problems are occurring with your
> '93 A/T or your '98 6spd? My '94 with A/T used to still trip
> a MIL occasionally due to the EGR, and I never did find that
> problem. I disconnected the EGR, put the bypass resistor in,
> etc. but no joy.
> 
> John
> '97 RSP 6spd APU hardtop
> 
> 
> --- On Sat, 9/12/09, Thomas Bradley <myothersupra at yahoo.com>
> wrote:
> 
> > From: Thomas Bradley <myothersupra at yahoo.com>
> > Subject: [mkiv] Codes 42, 71, and 89 simultaneously on
> hot days...  wth???
> > To: "The MKIV.com National Mailing List" <mkiv at mkiv.com>
> > Date: Saturday, September 12, 2009, 7:42 AM
> > Hi all,
> > Sorry for the length in advance!
> >  
> > I could really use some help from the MkIV tech
> guru's
> > around here, please.  :) 
> >  
> > I've got an issue that used to be constant when I
> bought
> > this car and a few things I've done have helped a lot
> but I
> > can't seem to solve it completely.. 
> >  
> > I keep getting Code 42, 71, and 89 together and I
> can't
> > find much info on code 71 or 89. 
> >  
> > I've done a few things and now it only happens on
> really
> > hot days and/or warm days when I drive for like 30-50
> miles
> > at highway speeds, especially with the a/c on,
> but it
> > happens without the a/c too and I don't know what
> else to
> > do to try and solve it... 
> >  
> > I clear all codes and drive a while, then BAM!  all
> three
> > simultaneously every time... 
> > Doesn't happen every day but probably 3-4 times a
> week,
> > especially in mid summer. 
> >  
> > Boosting hard or just cruising gently doesn't seem to
> make
> > any difference. 
> >  
> > I'll be driving along for a while then all of a
> sudden
> > Trac Off and MIL, followed by O/D Off flashing,
> followed by
> > C.E.L. all within about a second.  
> > Pulling over and turning the key off then back on or
> > parking the car for a while doesn't make any
> difference. 
> > 
> > They come back on with the key and stick around a
> while. 
> > If I keep driving for a while longer they will
> eventually
> > all go out one by one within a second of each other
> again
> > and stay gone for a long while.  It's rare to see
> them come
> > and go twice on the same drive.  
> >  
> > I think pulling the efi fuse will clear them
> temporarily
> > but I don't recall if they stay gone long or not if
> they
> > were active when the fuse was removed. 
> >  
> > In hopes of solving the code 71, this helped a lot
> but
> > didn't solve it... 
> > This trio of codes and lights used to happen almost
> > constantly when I got the car so now the EGR sensor
> plug is
> > disconnected and there's a 10k 1/2 Watt resistor in
> the
> > harness connector and the vacuum lines were
> re-routed/capped
> > to eliminate EGR, which seemed to help a LOT but
> didn't
> > solve it completely.  We don't have smog or emissions
> tests
> > here so EGR isn't critical for this car. 
> >  
> > Should've solved the Code 42, definitely helped a lot,
> and
> > may be unrelated.... 
> > When I got the car, even when the other lights
> weren't
> > on the O/D Off light was almost always flashing and
> the
> > cruise rarely worked so I resoldered the odometer
> circuit
> > boards like I've done on other MkIV's before and those
> two
> > problems went from constant to gone. 
> >  
> > I have no idea what Code 89 is all about and can't
> find any
> > info on it other than "Trac ECU". 
> > Trac seems to work fine, especially on rainy
> days...   :)
> > 
> > I'd love to pull a plug and disable it without having
> to
> > look at the trac light all the time but I can't seem
> to
> > figure out how on the 93 whose Trac ecu plugs are
> different
> > than my 98, especially with the automatic, so I just
> press
> > the trac off button when I want to play...
> >  
> > iirc:
> > Code 42 Speed Sensor #1 signal
> > Code 71 EGR Malfunction
> > Code 89 TRAC ECU
> > 
> > These are not random old codes from
> different/old/unrelated
> > issues, they all come on together. It always goes from
> none
> > stored to all three together every time this happens.
> 
> >  
> > The cruise still works even while these codes and
> lights
> > are actively showing up. 
> >  
> > It seems to be heat or engine bay temp related as hot
> days
> > and/or using a/c on really warm days is more likely
> to
> > trigger it. 
> >  
> > I don't get what these three things have in common. 
> >  
> > Any guidance would be greatly appreciated...
> >  
> > Thanks in advance!
> >  
> > 
> > Thomas
> > myothersupra
> > --------------
> > 98TT 6-Speed MkIV
> > 93TT Auto MkIV
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> > 
> > 
> > 
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> 
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