1992 Nissan Maxima Transmission Shift Control Problem.

Tiny
NUY351
  • MEMBER
  • 1992 NISSAN MAXIMA
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 20,800 MILES
I power washed the engine and transmission of my 92 maxima SOHC engine type VG30E. I usually clean my engine/transmission twice a year. After this washing the transmission immediately began shifting very erratically, "i.E." Upshifting and downshifting spontaneously as well as slipping out of gear. Have I water contaminated a shift computer or shift govenor? Will blowing all electrical weather connectors out with high pressure air be of any benefit? I've not experienced this before although this transmission was pulled and re-installed twice within the past 18 months. The car is virtually undriveagble at this point. Appreciate any thoughts.
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Monday, July 6th, 2009 AT 3:35 PM

13 Replies

Tiny
BUDDYCRAIGG
  • EXPERT
That's where I would start.

Is the check engine light coming on?
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Monday, July 6th, 2009 AT 10:07 PM
Tiny
NUY351
  • MEMBER
The check engine light never came on. I wish it had as I have my own OBD1 and 2 hand helds. Would make my life easier. I blew out all the weather connectors last evening but havent had a chance to road test the vehicle yet. I contacted the Nissan Dealer and learned a replacement Shift Control Computer will run $750 and change. Difficult for me to believe it's anything other than a short secondary to water contamination. None of my repair manuals (cheap ones) have a wiring schematic for this Shift Controler circuit. Will likely have to go to the public library to copy one. I am curious if there is a specific shift control relay under the hood that may have gone south, are you aware of a relay in this circuit?
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Tuesday, July 7th, 2009 AT 9:05 AM
Tiny
BUDDYCRAIGG
  • EXPERT
You can run a self-diagnostic test.

Phase 1
Run engine to normal temperature.
Turn ignition switch to OFF.
Set transmission mode switch to AUTO, overdrive switch to ON and selector lever to P.
Turn ignition switch to ON, but do not start engine.
POWER indicator light should come on for 2 seconds.

Phase 2
Turn ignition switch to OFF.
Move selector lever to D, over drive switch to OFF.
Turn ignition switch to ON, but do not start engine.
Move selector to "2" position, set overdrive switch to ON, move selector to "1" , set overdrive switch to OFF.
Press accelerator to the floor and release.
Record POWER light flashes.

Come back with the codes and I'll look them up on the chart.
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Tuesday, July 7th, 2009 AT 5:30 PM
Tiny
NUY351
  • MEMBER
Understood, will do.
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Wednesday, July 8th, 2009 AT 12:05 PM
Tiny
NUY351
  • MEMBER
Tried to run transmission diagnostic algorythm about half a dozen times--never could get the dash power light to flash any codes.

I'm still focused on figuring out this shift control circuit. I'm still thinking I've contaminated something with water when I washed the engine and I'm overlooking some connection or relay. I wouldnt rule out the shift control computer as being bad or the main onboard computer as being bad for that matter. I dont mind replacing computers at all as I've got good after factory vendors with more reasonable prices but I hate to replace a unit not knowing if that is the system fault.
I'll keep cogitating the issue and let you know if I find anything more. I'll review this web sites letter archives to see if I can spot a like problem and remedy.
Will be in touch. Thank you for your help.
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Thursday, July 9th, 2009 AT 2:48 PM
Tiny
BUDDYCRAIGG
  • EXPERT
Mmmm.
I didn't look to see if no codes at all was an option.
I assumed there would be at least an "all ok" code of some sort.

Did the power light come on in the first step?

I'll check tonight and post again if I have any information for you.
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Thursday, July 9th, 2009 AT 5:07 PM
Tiny
NUY351
  • MEMBER
Thanks for your response. If you mean the "Check Engine Light" when referring to the "Power Light" as the test protocol does the check engine light is illuminated whenever I have the ignition switch in the ON position. It naturally came on each time I ran the test protocol when I switched to ignition switch to the ON position as directed. It never gave me a make or break code flashing pattern during any of the test algorythms like I'm used to seeing with the older pre 90's computers.
SOOOoooo.I'm still stumped as to being able to pull up a fault diagnostic code.
I also noticed I mispoke yesterday when I stated I had both an OBD I and OBD II handheld. I do not have an OBD I tester. Used to use the old paper clip maneuver for reading those codes.
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Thursday, July 9th, 2009 AT 5:16 PM
Tiny
BUDDYCRAIGG
  • EXPERT
Ooooh.

It's the light with the letter P over it.
On your power/comfort switch.

You must of thought that I was crazy,
because as you said, the CHECK ENGINE light will come on anytime the key is ON and the engine is not running.

Sorry about the confusion.
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Thursday, July 9th, 2009 AT 6:33 PM
Tiny
NUY351
  • MEMBER
No need to apologize, so much technical language these days who knows what were talking about. Not like working on my 53 F250--whole different kettle of fish!
OK, now that I know which lamp to look for and where it's located I'll run the diagnostic again.
By the way, that 53 F250 is candy apple red with white diamond tuck leather interior and a Mopar 413 under the hood. She'll pull a stump or two if I need her to!
Thanks again for clarifying the test procedure for this old relic!
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Friday, July 10th, 2009 AT 2:20 PM
Tiny
BUDDYCRAIGG
  • EXPERT
PS, I wanted to tell you what you are looking for.
It wont be like what you are used to.

Say a GM code 12 would be flash, flash, flash.

These will be like morse code. Long, short, short, short, short, short.
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Friday, July 10th, 2009 AT 2:48 PM
Tiny
NUY351
  • MEMBER
I forgot to inquire as to were on line I could find a transmission vacuum line routing diagram. I dont find one in either my Chiltons or Hanes. Havent been able to locate one yet with an online search. The reason I ask is I found one vacuum hose disconnected on my inspection. This hose is a small one maybe 1/4 in dia like the ones on the master vacuum control. It is coming off the top center of the transmission Valve Body cover closest to the firewall. I've seen some references that refer to it as a Vent but that would surprise me as the vacuum line has a U shaped steel connector fitting at the terminal end as if it is designed to fit into the intake manifold or another hot mettalic surface. Any thoughts?
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Tuesday, July 14th, 2009 AT 11:51 AM
Tiny
BUDDYCRAIGG
  • EXPERT
I'll see what I can find, but often the vent hose is attached to a U shaped plastic or metal pipe.

But normally the pipe is on a bracket keeping it pointing down, so water can not get into it.
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Tuesday, July 14th, 2009 AT 5:27 PM
Tiny
BUDDYCRAIGG
  • EXPERT
Sorry, no pictures.
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Tuesday, July 14th, 2009 AT 6:28 PM

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