I finally have time to tackle the 90 240 cruise control again. The problem is in the vacuum pump circuit. If I put 12 volts straight to the pump, it works. However there is no voltage going from the module to the pump. I do have voltage at the module (Blue-Red wire and yellow wire). There is continuity between the module and the pump. My best guess is that the module is bad. Can anyone tell me how to check it further or to find instructions. This 90 system is different than any of the other 240 cruise controls. Earlier manuals don't apply.

Anyone know where I might find a working module? I've not found any listed online.

 

arghg, had a whole detailed reply that got lost when I closed my browser ... doy!


blue-red to the control unit is indeed power. black is ground. yellow appears to be the speed signal from the instrument panel.

short version: the 1990 control unit looks to be the same for 1989 through 1993 240's, so you should be able to find one from piknpull or whatever for any of those years. they are $438 MSRP and $328 at tascaparts.com, ouch. I'd want to be really sure that was the problem before buying a new one. if you can find one cheap off a parts car, go for it. looks like the control module is above the steering column, fairly deep.

the vacuum pump is attached to the control unit only, via 3 wires, and has no other source of power. looks like the yellow-red wire is the power source (only when the cruise control is turned on, and the green yellow wire is the current return for the vacuum motor, and the orange wire is the current return for a actuator coil (possibly to release vacuum?). these last two are drawn in 'pink' in the operation diagrams, which I think means they are either pulsed or partial voltage (solid red means 12V)

I don't believe it will power the pump if the car isn't going over 30mph, or if the brake or gas is pressed. it also won't work if both brake lights are broken (or presumably if the wire from them is broken), this runs like... yellow and yellow-green wire from tail lights goes to bulb out sensor. blu-red wire from bulb failure sensor can goes to brake light switch (which is powered by green-yellow wire from fuse 7) and also blue-red wire goes to brake switch (seperate from brake light switch), if you have a clutch it also goes through the clutch switch, and this signal lands on pin 3 of the cruise control module, as white-black(I think, my copy is a bit fuzzy)

 

Thanks for the detailed reply. I have worked out the wiring scheme, and it is as you say. The only thing I hadn't considered was the need to be doing 30 to activate the pump. This throws me a curve. I suppose the next step is to block up the rear wheels and run the speedometer up to 30-plus and see if it kicks in. If it does, I'm back to zero.

I finally found a shop manual for this model and am awaiting its arrival. Maybe it will show me some further tests. If nothing else, I'm slowly learning my way around in 90 240 cruise control.

 

The plot thickens a bit. I just ran the speedometer up to 40 mph with wheels blocked up. No current from module to pump with cruise control "on." However, I get a pulse through the R/Y wire when I push the set button. It just doesn't stay on. I hooked the pump up and tried it at 40+. Used a stethoscope to be sure I could hear it if it ran. It doesn't come on. I'm still thinking module malfunction, but will wait for the shop manual to see if I can make any other tests.

 

One more test: I put a milliampmeter in line between the yellow wire and the instrument panel connector. The yellow wire connects to the speed sender. No current shows even when I run the car up to 50 mph. This yellow wire shows "hot" where at the module, as does the blue-red wire.
Could be something burnt in the speed sender? I have already inspected the instrument panel circuit board carefully and see no breaks or burnt spots.

 

the speed sensor signal is most likely pulses of voltage, rather than any signficant current. a DVM with a 'hz' frequency mode should read a variable frequency depending on speed, relative to ground.

 

Thanks one more time. Seems to be narrowing down to the module. I'll see if I can find a scope locally to check the frequency.

 

If you are anywhere close to a Pik-n-Pull type yard, just get the parts for next to nothing and swap them, much better way to go... They should be plentiful and cheap. I got a whole Volvo Cruise Control (all pieces) for $15.

 

Unfortunately, SW New Mexico isn't exactly Volvo country. I'm 40 miles from the nearest new parts store and 100 from an auto salvage yard of any kind. I just received a Volvo shop manual for this cruise control system and can see a couple more things I need to check before I buy parts. Will keep you posted.

 

Were you able to check the yellow wire to see if there are any pulses on it? For this you will probably need an oscilloscope. However, I expect that you are getting pulses on it. If not, I would expect that the ECU would be throwing a 3-1-1 code and I believe you checked that in the past.

The output of the speedometer chip (ITT 2115) feeds both the yellow wire and the ECU with pulses that are relative to the speed of the car. If the taxi output of the 2115 chip is blown, you won't see any scorch marks on the speedometer circuit board but the cruise control won't work and the ECU will thrown the 3-1-1 code. You also may see some idling wierdness when coming to a stop. Basically it will feel like the engine might die when coming to a stop.

Good luck

 

instead of a scope, you probably could read these pulses with a digital multimeter that has a frequency mode, reading in Hz (cycles/second)

 

I haven't come up with a oscilloscope or a multimeter that reads frequency. However, the shop manual arrived, and I systematically retested everything following it through step by step. This process disconnects all of the circuits from the module and tests them individually. If they all test out, then the module, according to the book, is the culprit.

Such was the outcome of my tests. All circuits are as they should be. I notice no idling problems, and did not get a 3-1-1 in my earlier tests. Right now I have a request out in an online Volvo salvage search web page, hoping I can find a serviceable used module (risky, I know) at a decent price. In the meantime. If I come up with a scope in the meantime, I'll test the yellow wire. It does show continuity for the appropriate test following instructions in the manual.

Here is a related puzzle: The tab on the back of the instrument panel where the yellow wire attaches is divided to accept two wires. The only other wire back there that fits the second tab is a red and white wire. I've scanned the wiring diagrams and the only thing I can figure out that it does is activate a ash tray light. This makes no sense. Do you have any idea what the red/white wire might be. I can't see anything not working when it is disconnected and am tempted just to leave it loose.

Once more, thanks for all your help. I'm definitely a bold amateur who often gets in trouble.

 

according to my wiring diagram for a 1990 240, the other wire off the same output on the speedo is blue-black and goes to the up shift indicator circuit on a manual transmission equipped car and to the LH 2.4 jetronic ECU pin 34.

 

Sometime back I was at the local Pull-A-Part and found a cruise control stalk for the steering column. But the engine in that car was long gone and so I didn't get any other cruise control parts.

I just got an email saying that there are now two more 244s there and I would like to run down to see if there are any cruise control parts. But I have no idea what I'm looking for. Where can I find a schematic or diagram showing me what all I need to score from those cars?

 

the actuator and the control unit are above the pedals, not the engine. however, there's a vacuum pump near the brake booster on the firewall. there's also an additional pedal swithc or two, and of course, the wiring that hooks it all up.

 

To woodenyouknowit: The Bentley manual has pretty good photos of locations of components for 83-85 and 90 and later 240s--pages 360-12 and 360-13. The wires all disappear into bundles, so I'd hate to have to try to extract them.

 

To Pierce. Your knowledge and help much appreciated. Based on your comment, I'm guessing the R/W wire goes to the ECU pin in my automatic 240. Will therefore leave it attached. So far no replies on my search for a used module. Looks like I may have to break into my piggy bank and buy a new one.

 

The red/white is for the tachometer if you have one. Do not connect it to the extra tab where the yellow wire plugs in. Doing so is what frys the 2115 chip (trust me, I know). Reading over at brickboard, this is a common mistake. If you don't have a tach, the red/white wire does not connect to anything.

 

OK, that r/w wire has been connected all along. I can't tell you when that happened, but no doubt the chip is fried. I'm glad I haven't bought a module yet. I'll find a hz meter of some kind to confirm the chip problem. Am I right that I'll have to replace the instrument cluster or will just a speedometer (if I can find one) do the job?

The r/w wire is now disconnected for good. Maybe down the road I'll buy a tach.

 

I wonder how much trouble it would be if I were to buy an aftermarket cruise control and adapt it to the stock Volvo turn signal control thingy.