V70 Cruise Control tripping off

My '01 V70 XC has a great cruise control unit, but sometimes when, after turning on the cruise control control but before setting the speed, the unit will trip off when you touch the set control (the "+" switch). Then the cruise control cannot be turned back on with the cruise button unless you shut the ignition switch off and then back on. The cruise does this about once or twice a week. It seems to be a random event that only occurs when attempting to set the cruise. It does not occur when using the "+" switch to increase the set speed or when using any other switch.

I have gotten so I can put the transmission in neutral, turn the ignition off and back on, and restart the engine without slowing down or stopping, but I would like to get this fixed. I am afraid that the dealer will just start throwing my money at it like he did when I needed a pnp switch on my 850's transmission.

I suspect it may be a software problem. I am guessing that the cruise operates off the main computer. Any hints to help me limit the good stuff the dealer will replace in trying to solve this is appreciated.

Reply to
Stephen Henning
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PS: I have never had the Throttle Control Module replaced. I don't know if this could be related to that.

Also, when idling, the engine stumbles. That is the rpm's drop suddenly from 700 down to about 650 and then jump to to 850 and then settle down. These stumbles occur about every 15 to 30 seconds or so.

Reply to
Stephen Henning

If you had a throttle problem the car would stall and you would have to wait a minute or two before the engine would regain any power. I have been through it... This sounds like electrical problem. In the fuse box there are two relays that control cruise control - they labeled 101-102. Check them out...

-Peter

Stephen Henn>

Reply to
Peter Ziobrzynski

Reply to
Mike F

This problem only occurs when I touch the (+) set button. I don't see how a fuse problem could occur only when I touch the (+) set button. Once engaged, the cruise works perfectly.

Reply to
Stephen Henning

Thanks Mike. Once again I think you have solved a problem for me. I have started experiencing on rare occasions a dead response when I try to accelerate from a stop. Sort of like when I leave the geartronic in

3 at a stop and expect it to be in 1. It always recovers quickly. I guess I will have to convince my dealer that I need the TCM replaced under the extended warranty.
Reply to
Stephen Henning

I had the similar symptoms with my 2001 V70 2,4T last year. Happened to be so, that cruise control trips off as a precautionary measure. Thus there were much serious problems in our car, and voila, after replacing air flow mass meter AND ETM, the car has been fine.

Goes without saying that hurt my wallet quite a bit.

Reply to
Kytis

Reply to
Willy VINKEN

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