92 Q45 power steering + speedometer simultaneous failure

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myf16
Posts: 63
Joined: Tue Aug 29, 2006 12:17 pm
Car: 1994 Q45

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I searched and found one thread with some information on steering: zerothread/108521

This problem appears to have an electrical root. My son reports that the speedometer dropped to zero but everything else appeared normal (including tachometer), and the power steering got very heavy at all speeds. There were no fan belt noises, and steering fluid level is normal. Re-starting the car later, the problems were gone.

One other possible clue is that he reports the cigar lighter power dropped out during this failure.

I see several possibilities:

1. Shaky ground connection, but where?

2. Faulty speed sensor or loose connector to it.

3. Shaky power steering solenoid, but that doesn't explain the speedometer dropout.

4. Faulty power steering control unit. This connects to the speedometer and perhaps could cause the speedo to drop out. Does anyone know if that's possible?

I'd sure appreciate some ideas here. I'm going to put the car on stands tomorrow and check for loose connectors to the speed sensor and the power steering relay. After that, I'll be stumped.

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Q451990
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Car: 1990 Q45 - 118K, 2022 Toyota 4 Runner, 2004 Frontier M/T - 108K, 2012 Xterra (Mom's), 2023 Rogue (Inlaws)
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Check out these threads. The only thing that seems interesting is a loss to the cigarette lighter. It's almost like part of the ignition switch is dropping out...?

zer...45093

zerothread?id=299603

Do you have the factory service manual for your '91? It was included with the car and is usually found in the trunk or storage bin between the rear speakers.

If not the closest you can find online is for a '94. http://www.nicoclub.com/FSM/

Heath
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myf16
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Car: 1994 Q45

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Fascinating reading. I never would have fingered the circuit board in the cluster (post 4355730), but that certainly sounds like the culprit if the speed sensor wiring is not loose. Replacing the cluster is easier than many other repairs I can think of. I once had to replace the power steering pressure lines on this car and that was a nightmare.

I don't know if the cigar lighter observation is reliable, and I doubt any relationship until I see it myself. Sounds like I have some road testing to do, then I have to find a relatively low mileage cluster. This car has 160k miles, and it will be tough to find a 1992 with less than that.

Thanks for locating those threads for me. Oh, and yes, I have the factory service manual. I did the troubleshooting for the brake switches and transmission gear sensors, but that's as far as I got. I don't think their fault tree included the cluster or the speed sensor, so it looked incomplete to me. That's when I decided to get serious and ask here!
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goody90q45
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Joined: Wed Aug 17, 2005 2:07 pm
Car: 1992 Q45 (sold)
Location: Orangevale, CA

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It never made sense to me either that a component in the instrument cluster can make the PS fail. You would think that as long as the pump was functioning and the belt was on that it would never fail.
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Q451990
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Here's one on eBay. http://cgi.ebay.com/ebaymotors...ories

The failure isn't super common, so I would think you might have a pretty good chance of getting a good one. You can swap the odometers from cluster to cluster to keep that accurate. Of course you'll want to follow all of the steps in the FSM first to be as sure as possible before you start ordering parts.

Heath
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myf16
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Car: 1994 Q45

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Problem resolved.

Replacing the instrument cluster did not fix this problem, but replacing the speed sensor did.

The old speed sensor was not obviously damaged in any way, nor was the connector loose. Despite a post I found somewhere to the contrary, removal and replacement of the speed sensor was entirely straightforward.
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Q451990
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Good to know... thanks for posting back and telling us what fixed it for you.

Heath
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Q45tech
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Posts: 14365
Joined: Tue Apr 30, 2002 3:19 am
Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl

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If people bother to read , THEN STUDY the FSM circuit diagrams they would see a test terminal in the CONSULT SOCKET for measuring the voltage from the cluster circuit board vs speed,
Things besides PS depend on this 0>5 volt signal.

I can't wait until people get exposed to all electric steering.

A two year trade school course in electronic technology would help everyone especially doctors, lawyers, and business people plus housewives, even hookers.
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Infinitiguy19
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Joined: Sat Dec 22, 2007 4:58 pm
Car: 1993 Infiniti Q45 188580 Miles
1994 Infiniti Q45a 240000 Miles

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Q45tech wrote: I can't wait until people get exposed to all electric steering.
Electric steering is a joke because if it fails, your f***!
Q45tech wrote:even hookers.
:lolling:

Good to know in case I need any help. :)

Police officer: What are you doing with that hooker
Guy: She is just fixing my car...
....
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myf16
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Car: 1994 Q45

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Q45tech wrote:If people bother to read , THEN STUDY the FSM circuit diagrams they would see a test terminal in the CONSULT SOCKET for measuring the voltage from the cluster circuit board vs speed,
The fact that this failure was intermittent made diagnosis difficult. My son told me later that otnly in drives more than 10 minutes did the failure appear. I suspect that the transmission had to get up to temperature before the speed sensor cut out.

On the bright side, I am now very adept at changing the instrument cluster. :)
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Q45tech
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Posts: 14365
Joined: Tue Apr 30, 2002 3:19 am
Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl

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The problem with late80's electronics in CARS vs HOME/OFFICE enviroment is wide swings in temperatures from zeroF to 200F sometimes daily.

Going to the moon in a space ship only lasted a week yet many expect vehicle electronics to last 20 years
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myf16
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Car: 1994 Q45

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Update: Replacing the speed sensor solved this problem.
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Q451990
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Car: 1990 Q45 - 118K, 2022 Toyota 4 Runner, 2004 Frontier M/T - 108K, 2012 Xterra (Mom's), 2023 Rogue (Inlaws)
Location: Columbia, SC
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Thanks for letting us know!

Heath
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