960 speedometer/transmission problem.

[IFGD]

Hello all, first post here. I have a 1994 960 that I use as a second car to haul stuff around. I drive a Mazda Miata most of the time.

The problem is intermittent, some days the car is a dream to drive (with 240K miles!), other days it has trouble.

Bottom line, if the speedo is working, the car is great. If the speedo isn't working, it won't come out of 1st gear. Sometimes it goes to second when the speedo is dead, but when it does, it doesn't stay in second very long.

I've tried pulling over and turning the car off and restarting it, but that doesn't seem to work. I'll get it home, turn it off and the next day, it drives like new.

Any ideas?

Thanks!

[billofdurham]

Welcome to Matthew's Volvo Site.

The transmission needs the signal from the speedometer along with signals from other sensors to work correctly.

The AW 40 gear box is fitted with a self diagnostic capability. The instructions for its use are pinned at the top of the forum. Run a check for fault codes and post back with the results.

Check the connection at the speedometer sensor. You'll find it in the differential cover about 3" above the filler plug. Be sure it's mechanically secure and check the contacts on both the sensor and the connector for signs of corrosion or oxidation. Examine the wiring for any signs of a break or for signs the wire might have been cut. If it's not a wiring fault then it's either the sensor or the speedometer head, which is electronic. It is possible that the power supplied to the speedo head where it's mounted in the dash cluster is intermittent. Check that the connector on the back of the speedo head is secure. Check the instrument cluster earths (grounds) behind the right kick panel.

Bill.

[tyler206]

i am having this exact same problem in my likewise 94 960, only it has now progressed to the speedo not moving at all, and the trans never coming out of limp mode; complete with the blinking overdrive arrow/transmission mode selector buttons, which initially led me to believe it was related to the PNP switch, which i inspected and which visually appeared to be fine. i was able to fix the blinking temporarily by shifting through all the gears on the shifter a bunch, once or twice, however once the blinking lights returned, they now were accompanied by a speedo that wouldn't move above 0mph. the car is currently undriveable.
at first it was just like op described, intermittent. before the overdrive arrow came on, occasionally, while driving at higher speeds (around 45-60), the speedo would behave normally; instead, the tach would 'twitch' or bounce around seemingly sporadically--not corresponding to acceleration or shifting gears.
while it was still intermittent and i was trying to identify the problem, i had already done all the diagnosing bill suggested in his comment. checking the sensor on the rear diff, which looked perfectly fine but i cleaned it anyways. wiring to the sensor also looked fine, no visible cracks in the harness, no corrosion in the connectors, etc.
I also took apart the dash, to inspect the speedo head inside the cluster--all components looked fine except for a couple of solder joints that just required a hot poke with the soldering iron to make them like new again. all of the other connections looked okay. there are some lightbulbs in the cluster that need replacing and which appear to also be acting as connectors/conductors for the rest of the circuitboard? i could be wrong about this, as i'm very novice with this kind of electrical work; if someone could confirm whether or not that could pose an issue, please let me know. i have to order the bulbs as i can't get them locally in-store.
before all of this, i checked for codes on the obd, and it didnt return any at all. just 111. currently, after the abovementioned poking around at the electrical, the car still isnt returning any codes.
i am at a loss. this is my only car, my daily driver. my inability to drive resulted in my losing the job i had just started a week before all this started. living rural where i do, where there is no public transportation, i am out of luck to find work again until i get this fixed; thanks to losing my job though, i dont have the money to take it to be professionally diagnosed and repaired. i normally do all the work on my car myself, and i enjoy it, so i'd be happy to fix it myself, if i could identify the problem. any help greatly appreciated. surely there must be something i'm not thinking of, because this has me stumped.

[Batevv]

I have exactly the same issue as you do - no errors. Speedo works. PNP switch is new. Checked and fixed all connectors and grounds but car shifts to second gear if I push it to 4000-5000 rpm and return the gas. Oil is new, transmission is 10-15k after rebuild.
Any ideas? The car wasn't used for 10 days and started doing this. I ahve a broken gearbox which I used sensors and other stuff from. Changed the TPS with new but nothing helped. Engine works good. Coilpack harness is a mess but I will replace it once the car is drivable.

[Batevv]

Just did a lot of digging. The problem is from the speedometer board:
https://www.volvoclub.org.uk/faq/Electr ... Repair.htm

Its an easy fix