QuestionQUESTION: Hello Roland,
The speedo and odo in my LB quit working. I noticed that the mpg computer also is frozen (accumulates no miles and shows 0 mpg).
I tried replacing the speed sensor and gear with a used one I had from a junk car, but all is the same. I am waiting for a new speed sensor in the mail.
I cannot recall how to check the sensor, or, if the new one doesn't solve it, I don't know where else to look.
BTW, the sensor I took out was the old style (with speedo threads) with a cap over the speedo threads (not used). The speedo doesn't use a cable. The used one I put on was the kind without any speedo connection.
Thanks,
John
'89 GTC 2.2TII A555
ANSWER: Hi John,
The sensor produces some sort of electrical pulsation (probably voltage) so that if you lifted the front wheels off the ground you could power the sensor while in place and monitor the output on its two wires. It plugs into a two-pin disconnect where the black/light blue is a common sensor ground and the white/orange goes to pin A of the red plug at the mechanical cluster.
On the way it passes through a rectangular black 10-pin disconnect at the rear of the battery.
The white/orange also goes to pin 48 of the smec from that disconnect and to pin 4 of the trip navigator for the mpg calculation. It may be that the pinion gear on both speed sensors you have now is damaged. That can happen if the right side half-shaft is removed from the transmission without first removing the sensor from the transmission. So use a voltmeter and/or an ohmmeter across the output of the sensor while you rotate the pinion gear by hand to see if you have a signal. Let me know what you find.
Please read the PS below and respond.
Thanks,
Roland
---------- FOLLOW-UP ----------
QUESTION: Hi Roland,
I tested the original failed sensor and it was flat all around (no continuity-no pulsing in resistance). I went into my stockpile of parts and found yet another (number 2 used part) sensor. It pulsed continuity (on then off) as I spun the pinion gear. I took out used #1, put in used #2. It works! I tested used #1 (which didn't operate the speedo) and it tested good. I suspect that, yes, the gear was not meshing right as it was very difficult to get to mesh and seat down.
AnswerThanks for the positive report of the distance sensor pinion gear being the problem. I will share that with others by making this a public q and a. Thanks also for your kind remarks, rating and nomination. Feel free to do that again is you would like.
I have the same year as you, coupe model (2.5L with A-413) and it continues to please me.
Roland
