After swapping out the blower motor and blower motor resistor on my 1986 Volvo 240 DL I put everything back together and now overdrive no longer does anything (no light on the dashboard or overdrive kick when driving) when I press the button to engage it on the gear shifter.

What I've checked so far:

• All of the fuses by the lower driver's side foot panel are good.
• The white overdrive relay that lives on the railing near the glove box gives a reading on my multi-meter when it's pulled out and tested.
• The plugs that are between the overdrive relay and the gear shifter are fully plugged together

 

you can test if the overdrive relay is working by taking it out and jumpering pin 15 and 87 with a paper clip. does this allow the trans to shift into 4th gear? if so the relay is bad.

 

I had tested the relay already while it was pulled out with my multimeter but I did your paperclip test now as well since it sounded like a good way to double check my work and I still have no overdrive with a paperclip on pins 15 and 87. I turned the car on, put it into drive, and the overdrive light in the cluster doesn't go on when engaging the overdrive button on the gear shifter.

 

the light indicates OD is disabled.

the only way to know OD is working is to drive fast enough for it to make that 3rd shift into OD. these should go into OD as slow as 40 MPH if you're just coasting along with very little throttle.


I'm not sure how you think you can test a relay with a multimeter? you need to supply 12V to the relay power pins, then verify continuity at the NC switched pins of the relay, momentarily close the button pin to toggle the relay state, and verify the continuity changed to the NO pins.

 

Hi Pierce...

So are we saying that this video where the guy details how to test an independent relay with a multimeter is completely off base? Because that is indeed how I tested the relay independently with my multimeter.

As far as driving the car at 40mph to test it with the paperclip, sure I get your point but keep this in mind: the dashboard light and the overdrive worked before I took the car apart. Once it was put back together, AND driven, the dashboard light and the actual overdrive functionality both do not work, so I'm thinking they are tied together as far as not working. Sure I can drive it and test it with the paperclip, and I might soon, but it's tricky with the front carpet and everything pulled back.

 

the OD relay is a little more complex than a simple relay, its a toggle relay, so his test (I'm not watching 7 minutes of him droning on about what could have been shown in 1 paragraph and 2-3 pictures) isn't directly applicable.

so you used a battery across the power leads, and verified the relay toggles open and close when you tap the input to ground ?

the way the automatic overdrive is wired, when the dashboard light is OFF, the OD solenoid in the transmission is powered on. when the light is ON, the solenoid is turned off. when the solenoid is powered on, the transmission can automatically shift into OD/4th as needed. when the solenoid is powered off, it will not shift into 4th/OD.

to test the OD relay on its own, you'd connect 12V to pin 15, ground(-) to pin 31, and a light bulb or volt meter to pin 87 or 87a (same thing). you'd then use a jumper wire to momentarily ground pin 86, each time you do this, the light bulb or volt meter should toggle from on to off or back.

The OD light is connected to pin 87a and the other side of the OD light is connected to 12V so when pin 87a is powered, the light is off, when pin 87 is grounded, the light is on. The OD solenoid is also wired to pin 87 but the other side of the solenoid goes to ground, so when 87 is powered, so is the solenoid. so the paperclip from 15 (power) to 87 (OD solenoid) will NOT light the light bulb as thats connected to pin 87a... it will power the solenoid, and the only way you know the solenoid is working is to drive the car fast enough for the transmission to shift into 4th/OD.

 

what we're trying to do is eliminate the relay in the circuit to see if the problem maybe lies elsewhere....

 

Gotcha Pierce, I'll run these tests tomorrow. I wasn't aware that the dashboard light is triggered separately.

 

Ummmmmm.... obviously lol?!? And I'm trying to say that as nicely as possible since you are of course trying to help me (: That's why in my original post I mentioned the testing of the relay with my multimeter but of course now Pierce is pointing out that might not even have been the correct way to test it... I'll message back tomorrow with more info after I do the further testing Pierce mentioned in his last post...

 

well it should be .. but we have experience that all that seems obvious isn't when it comes to this o/d system.
best way i found is go through things from easiest to hardest... if you know what i mean? Of course you could always just bypass everything with
a block off plate....and not deal with it at all....
good luck

 

Yes I understand.

I did see about the bypass, or block off plate, as you call it. It's an idea BUT I'm a get to the root of the problem kinda guy, especially since all was working with the overdrive before I took the car apart. So I'm sure it has the ability to work again rather easily, as soon as I find the issue.

 

for me it was chafed wiring leading down to the solenoid so the failure was intermittent...and a bad relay so 2 issues.
the bypass / block off plate is an option but i found my problem areas before deciding to use one.

 

Or try this method. I used this kit on my '92 and '93 245 recently.

https://www.ipdusa.com/catalog.asp?n...drive%20bypass

 

I hooked up a paperclip to leads 15 and 87 of the socket, with the overdrive relay removed, and with the car running it gave a little spark when both were first touched to their leads simultaneously, so that makes me believe power is getting to the jumper I created. Once the car was driven at speeds of 40mph and above, with the paperclip in place, nothing still happens when the overdrive button is pressed.

Any idea what to check next? I'm ruling out the overdrive relay for now since it's being bypassed with the paperclip.

 

ok so you are saying when you are rolling at least 40mph with the relay out and jumpered you still get no 4th gear? doubt the light would work if the relay is out...
just to clarify...

 

Correct on all fronts including the light still not working when jumpered.

 

ok then the issue lies downstream of the relay in the wiring going to the solenoid or the solenoid itself.
as pierce has said the solenoid needs 12v to operate o/d. so need to check that.
honestly if i had to do it again i would install the bypass plate instead of trying to mess with wiring etc and be done with it.
i have never had the occasion to use the shifter button to eliminate o/d even though it works in my car...but i definitely
could not live without 4th gear...

 

I misunderstood what you said earlier. All of my gears, including 4th gear, work just fine. It's just that I am getting no overdrive since I did the recent work on my car. I also get no overdrive when testing it with the jumper paperclip in place.

 

I already carefully explained, the light won't work with the jumper in place and no relay. the goal is to verify that the car actually can SHIFT into OD with the jumper there. from a full stop, with the transmission in drive, accelerate gently and count the shifts, you should feel 1->2, then 2->3, then finally somewhere around or above 40 MPH, you should feel the 3->4(OD) shift. at each of these shifts you should feel the engine RPM drop.

now all this started when you reassembled the dashboard? IIRC, there's at least 2 3-pin connectors along side the transmission hump near the back edge of the center console. one of these is for the OD switch and solenoid, another is for something completely different, like the park/neutral switch. maybe you got them swapped ? Unluckily, my VM with the ancient OTP 240 wiring diagram software has decided to stop working, so I can't consult them to verify the wire colors on both sides.

 

Pierce you're likely on the correct path here regarding the pin connectors and switch and solenoid and one of your fantastic diagrams would be great once you can gain access to it... tx.

And to re-confirm, all of my gears shift fine (and I did hear you the first time about the dash light not working when jumpered), the car drives fine, I am just not able to activate the overdrive feature that worked before I did the recent work on my car.

To understand the older Volvo's better are you saying that they weren't supposed to switch to 4th gear unless the overdrive button was used? That didn't seem to be the case for me as my car would drive just fine going above 40 (and still does). I would only use the overdrive button if I wanted a little extra kick.