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Author Topic: 2001 olds aurora no start - internal mode switch  (Read 3090 times)

Offline alexandjojo

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2001 olds aurora no start - internal mode switch
« on: August 01, 2011, 08:00:54 PM »
2001 OLDS - AURORA 3.5 L

Here are the codes that came up:

P1819 Internal Mode Switch No Start, Wrong Range

P1825 Internal Mode Switch Illegal Range

P1826 Internal Mode Switch Circuit C High

3.5L V6.

      I currenteley have a no-start condition. Will not crank.  Where the pcm supplies ground to activate the starter relay - on that circuit is not supplying ground.  There is 3 volts +.  I traced the lines the connector going into the trans.  I pin pointed the circuits and there is power (b+) and noticed there was no ground at the letter k part of the connector wich is ground.  So I stripped a little of the wire off and used a jumper wire from ground and was able to get engine turning over.  Cool right---not finished yet!  So instead of going through the hoopla of seeing that this vehicle had some tampering I corrected some of the wirring and ran a good ground wire straight from the battery negative cable connected to body.  Checked over the starter circuit and everything seemed 2 b kosher.  Try to start-up and nothing.  Battery voltage fine, there is deffinetely ground and can by-pass starter relay to check starter condition is fine and turning over engine. 
      Is the starter drver circuit (ground to relay) contolled by the trans range selector?  My scanner shows its stuck on 4th gear.  ty

Offline alexandjojo

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Re: 2001 olds aurora no start - internal mode switch
« Reply #1 on: August 02, 2011, 06:49:39 AM »
Sorry....I thought that since the component involved is internally in the trans that this topic would be under transmissions.

Offline Gus

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Re: 2001 olds aurora no start - internal mode switch
« Reply #2 on: August 02, 2011, 08:35:58 AM »
For the life of moi, I don't know why they put that switch inside the tranny.....for years it was outside attached to the external linkage......

Basically, the switch tells the PCM, what gear you are in....if the PCM does not see Park(or in some cases neutral), it will not ground the starter enable relay......also, I don't think it will fire the injectors either, so just bypassing the relay won't work.....

The old P/N switch just used one output for the starter circuit....the new switches, use an on/off output from each range, to the PCM, so ineffect it is testing the output of 7 switches in a 4 speed tranny....

This is very easy to check with a scan tool capable of reading the output of the switch, like a Tech II....it is a pain in the ass to replace....

Offline kev2

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Re: 2001 olds aurora no start - internal mode switch
« Reply #3 on: August 02, 2011, 08:59:55 AM »
some thoughts.....as time permits I will follow up
  hopefully no remote starter? did you check for VAT codes?  my wiring Dia shows a "rear integration module" and I am looking for a Dia of that to post....

Offline alexandjojo

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Re: 2001 olds aurora no start - internal mode switch
« Reply #4 on: August 02, 2011, 07:31:22 PM »
Well guess what >:(,  just tried 2 check the PCM for codes again.  No response from the computer.  Checked the fuses with my digital fuses and seen that the right side of the in the engine compartment shows only 6.5 volts!  I am not near vehicle at moment but could remember somewhat that the fuses involved started with an hd letter and was not familiar where goto? (will post again on fuse part). Does the IMS involves taking down the trans or is there enough clearance to take side cover off?  My manuals does not provide me with this info.

Offline kev2

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Re: 2001 olds aurora no start - internal mode switch
« Reply #5 on: August 02, 2011, 08:08:11 PM »
Here is what I have  :(   hoping someone has a "cheat"  without R&R Trans


Internal Mode Switch
Removal & Installation
To Remove:

Remove or disconnect the following:
Transmission from vehicle
Fluid pan
Use side cutting pliers in order to remove the manual shift shaft pin.
Manual valve link from the manual shift detent lever or the IMS/detent lever assembly
NOTE: The IMS/detent lever should be removed as an assembly.

Nut from the manual shift detent lever
Manual shift detent lever or the MS/detent lever and remove the park pawl actuator assembly.
Position the transmission so that the reverse band servo bore is facing upward.
Pull the manual shift shaft out of the case.
Use a small screwdriver in order to pry the manual shift shaft seal from the case.
Remove or disconnect the following:
Park pawl actuator guide pin.
Park pawl actuator guide assembly from the case.
Actuator guide seal from the guide.
To Install

Offline Gus

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Re: 2001 olds aurora no start - internal mode switch
« Reply #6 on: August 03, 2011, 09:00:06 AM »
Think your battery is dying.......

Offline nickb2

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Re: 2001 olds aurora no start - internal mode switch
« Reply #7 on: August 04, 2011, 04:07:49 AM »
The lever assembly-manual shaft detent with internal mode switch (IMS) is a sliding contact electrical switch assembly that corresponds to the PRNDL position selected. Each of the PRNDL positions has a unique ground pattern on four wires from the PCM.

The assembly consists of two major components:
       The internal mode switch that consists of:
       -    The housing (1), which makes up the stationary contacts.
       -    The insulator (2), which makes up the moving contacts and is secured on the detent lever (4).
       The lever assembly which consists of:
       -    The manual shaft (3)
       -    The detent lever (4)

The range detection is accomplished by securing the moving contacts to the detent lever. When the driver selects a PRNDL position, the detent lever inside the transmission rotates. This rotates the insulator which in turn grounds the four wires in a unique pattern for each gear selection, corresponding to the PRNDL position selected. The IMS is electrically connected by five wires (four of which the PCM supplies voltage to and one wire that is a common ground) to the transmission pass through connector.


Try adjusting the shift lever cable first and see. Here is how;


    Notice: Adjust the shift control cable only while the transaxle and the gear selector are in NEUTRAL. Failure to do so may cause mis-adjustment.
    Set the parking brake and chock the wheels.
    Remove the range selector cable terminal from the transmission manual shaft lever pin.
    Pry on the range selector cable terminal at the manual shaft lever pin with an appropriate tool. Prying or pulling up on any other part of the range selector cable may result in damage to the range selector cable .

    Object Number: 97542 Size: SH
    Click here for detailed picture of above image.
    Fully lift the adjuster lock button. Ensure that the adjuster is free to move.
    Place the transmission manual shaft lever in (N) Neutral. In order to find (N) Neutral, rotate the lever fully counterclockwise to (P) Park, and then clockwise 2 clicks into (N) Neutral.
    Place the gear shifter inside the car to the (N) Neutral position.
    If adjusting a column shift vehicle, rotate the shift lever to the LOW 1 position, fully down. Push forward and upward slowly past the first click, which is overdrive, until it stops solidly at the second click. It is in (N) Neutral.
    Underhood, grasp the range selector cable terminal and pull it toward the pin on the manual shaft lever. The range selector cable adjuster spring should compress as the terminal is moved toward the pin.
    Attach the pin to the lever by pushing down carefully until it snaps.

    Do not pull the terminal beyond the pin and then push back. This action could move the shifter out of (N) Neutral.

    Object Number: 97544 Size: SH
    Click here for detailed picture of above image.
    Press the adjuster lock button down flush with the adjuster body.
    Shift to (P) Park and release the parking brake while applying the service brake.
    Start the engine and assure all of the indicated gear positions match the vehicle response.

When it don't work, hit it!!!


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Offline alexandjojo

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Re: 2001 olds aurora no start - internal mode switch
« Reply #8 on: August 06, 2011, 12:03:16 PM »
     I will give it a try on the adjustment......but on my scanner it does still show its on 4th gear no matter what selector i try to put it on.
    Also, if it comes down that the trans has to come off and dont have a car lift, would the motor and trans need to be pulled out together in order to gain access to the switch itself?   ouch
     My manual only says to take off side cover and go from there....

Offline Gus

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Re: 2001 olds aurora no start - internal mode switch
« Reply #9 on: August 06, 2011, 02:38:30 PM »
Yeah, that's a joke sometimes....just remove the side cover....if only it was so easy.....

But before you do that, exhaust all possibillities....since you have a scan tool, does it read that it is in Park, when it is in park?

Offline alexandjojo

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Re: 2001 olds aurora no start - internal mode switch
« Reply #10 on: August 15, 2011, 09:46:54 AM »
No it reads that its in 4th gear in any selector

Offline Gus

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Re: 2001 olds aurora no start - internal mode switch
« Reply #11 on: August 15, 2011, 10:21:56 AM »
Then that's the problem.....no car with an automatic transmission will crank over if it "thinks" it's in fourth gear.....Has to "think" it's in Park or Neutral....

Offline alexandjojo

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Re: 2001 olds aurora no start - internal mode switch
« Reply #12 on: August 25, 2011, 10:49:48 AM »
OK, I am attempting to r and r the part.  By looking at engine underneath the vehicle (since I do no have info or manual on removal of side cover) I am considering to to put my engine hoist to hold the engine in place (or suspense) and removing the lower subframe and then lowering down the engine-trans together to gain access to remove the side cover.  If there is another way please let me know before attemping.  Do not have a car lift.  Thank you.

Offline alexandjojo

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Re: 2001 olds aurora no start - internal mode switch
« Reply #13 on: August 25, 2011, 04:09:38 PM »
OH, forgot to mention the ecm no response deal was that the battery was low.  Charged it up and still had a problem with ecm no response at time.  However, I noticed that there was a ground wire bypassed to the ground circuit leading to the ecm not connected. Connected it and had ecm response with same codes again.  Sorry, I just forgot. But still need to know whether taking engine out with trans is better or someone has better solution? ???

Offline nickb2

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Re: 2001 olds aurora no start - internal mode switch
« Reply #14 on: August 26, 2011, 06:22:30 PM »
No lift? Better to unbolt the whole sub-frame assembly and disconnect the suspension at ball joints, tie rods, and steering rack and disconnect all electrical going to engine and tranny and just jack the car up to discover the side cover while leaving sub frame on blocks of wood close to ground. Don't forget to unbolt the mounts attached to car unibody.
When it don't work, hit it!!!


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