Speed sensor on Q45 or speedo cluster causing loss of power steering?

[pahrding]

I have a 91 Q45 with 125,000 miles. The speedometer has recently, and intermittently started cutting out and seems to stay that way until the carhas been parked usually overnight. The other issues accompanying this problem are that the power steering needs a lot of muscle at low speeds, and if the problem has not corrected itself since last parked, there is an error message of "transmission malfunction". The transmission seems to function o.k. regardless.

Would a cluster failure cause lack of power steering, or would it more likely be caused by the speed sensor.

I have trouble identifying the actual speed sensor unit on the transmission . I can see a small 1" round plastic can sticking out of the transmission case on the rear pass side. Approximately how long should the terminal cable be that comes off it? Does it go all the way to the speedo cluster or plug in to another cable that goes there?

[CGB]

Hi. I had the same problem and replacing the speed sensor solved.

Have a look; zerothread?id=148766

Good luck!

CGB

[pahrding]

Appreciate the information. I will get hold of a replacement speed sensor and put it in as soon as my garage drops under 110

[Q45tech]

If the speedometer displays accurate speed then the sensor is ok,

Then you look to PS steering electronic pressure controller module or in rare cases the signal divider IC which isolates the voltage feeds to PS, Speedo, AT and all.

Follow FSM to read the PS test voltage at the Consult connector.

[pahrding]

"If the speedometer displays accurate speed then the sensor is ok,"

By that do you mean that when the speedo works if it seems correctthen the vehicle speed sensor has to be o.k.? Does that also mean that the sensor would only fail totally and never intermittently?

[Q45tech]

Speed sensor and connector and cable to dash pc board can fail totally or intermittently. If steering goes hard and speedometer stays constant with speed then you look to ps pressure control module or wiring to ps solenoid or solenoid itself.

You read the voltage [ while driving] from control module to solenoid on a terminal in Consult socket.

All fully explained in FSM.

[mortimer9]

Q45tech,looking for answer to loss of power steering with loss of speedometer function intermittent.I read your explanation of loss of power steering with continued speedometer function. kevin

[elwesso]

IF the speedo fails at the same time as the PS, then I would first replace the speed sensor (quick and easy to replace).. Then i would move onto the instrument cluster, with the latter being more likely to fail IMO.