Hello, I'm sorry to post another overdrive question, but I've spent the last half hour searching and couldn't find the answer.

My daughter's 88 240 automatic will not shift into overdrive. The engine is spinning pretty fast at highway speeds. While on the freeway, if I push the OD button, the OD indicator arrow on the dashboard lights up, but I detect no downshift. I've also listened while accelerating from a dead stop and I can only detect two upshifts. It used to work, but I don't know how long it's been since it stopped, because my daughter has been away at school for the past couple of years. She didn't notice that there's a problem.

I'm assuming that the relay and circuitry are good, since the OD indicator light is working. Is that a bad assumption?

Also, the car is relatively low mileage, it has less than 100k on it. I did flush the trans a few years ago (as opposed to merely draining and replacing), but perhaps I should inspect the solenoid.

I would be willing to install the bypass plate, but it seems that won't help, because it's not upshifting to the fourth, or overdrive gear. Is that correct?

Any suggestions as to how to approach troubleshooting and repairing the problem?

Thanks!

 

safety neutral switch if it's not shifting properly...I owned an 87 wagon and had to replace this switch as it had a crack in it. It is easy to inspect it....

remove the plastic cover of the shift **** and the switch has two wires
It might not fix your problem but start there. On my switch the solder point that rubs as you select your gear, it was very worn and made contact once in a while until I chucked it...
The bypass plate would take care of the od but not the problem of upshift to 3rd 4rth or od, I agree with you there, makes sense.

what about the cable or link might need some adjusting?

 

I would check the relay first since they are prone to cracked solder joints on the little circuit board in the relay. To get to the relay, remove the glove compartment and it should be just to your left (center console). Pop the top off of it and re-flow the solder joints.

If that doesn't work, it could be a faulty solenoid. This is a little harder to replace as it is on the transmission and the bolts are a little tricky to access. IPD sells a plate to replace the solenoid that basically permanently enables the overdrive making it a 4 speed. They charge somewhere around $40 for it - which seems like a rip-off to me since it is just a metal plate. Search the forums here and someone described how to modify your solenoid to give you the equivalent using a dremel tool.

Good luck

 

It's either the relay which I would replace first and if that does not fix it then replace the solenoid. Usually when the relay is bad it will not shift into OD. Get the solenoid on eBay.

 

All a Neutral Safety Switch does is prevent the car from starting unless it's in Park or Neutral.

The IPD plate should help your condition, as described, although with such low miles your OD should be fine. Tranny fluid should be renewed every 20-30k miles.

 

Thanks for the responses. I'll have a look at the relay.

Meantime, can someone explain how the OD works? Is this basically a four speed trans? Is the purpose of the relay and solenoid just to move the trans from 4th (OD) to third? By installing the bypass plate, doesn't that just disable the button on the shifter? What happens if you just remove the relay? Will the tranny shift into OD at cruising speed?

 

This explains it well.

Transmission. Automatic AW70 and ZF

It's a four speed tranny, but the solenoid needs to be energized for the tranny to shift into 4th. It makes sense to check the relay first. I'll get to that in the next couple of days and will report back.

On a side note, it seems kind OD hokey to have a 1, 2, and D on the shift selector and a put button to go from 4 to 3. Why didn't Volvo just have a 1, 2, 3 D on the selector???

I've never owned a Volvo. Bought this one for my daughter on a recommendation by my neighbor, who has owned several. it's been a great car for her (and me), since she was 1000 miles away at shool. No problems whatsoever, except for this one. She apparently drove home from Eugene OR to SoCal in third gear...

 

the way OD is implemented on the AW7x transmissions, it really is a 3 speed transmission with a seperate OD gear for '4th'.

 

The solenoid was bad. I pulled it and verified that it was bad by bench testing with a 12V supply. So I did the mod that's described here:

Transmission. Automatic AW70 and ZF

It was pretty easy, five minutes with a Dremel did the trick, once I had it out, of course. It wasn't too difficult to remove, I had to lower the trans a bit to be able to get the wrench in there. For anyone thinking about buying the IPD bypass plate, don't bother!

I may get a new solenoid some day, but I'm not sure it's worth it. I doubt that my daughter would ever recognize a situation where it would be beneficial to downshift. In any case, the kickdown into third works just fine, if she encounters a long, steep grade. One less problem to deal with.

Now I don't ever have to worry about the relay malfunctioning either.