Hi, New member, and trying to figure out why my volvo cuts out. (just started doing this yesterday). On freeway using cruise control doing about 70, tap the breaks to slowdown due to traffic, then hit resume button (i am maybe doing 60-65), car lunges then engine dies.... I put in neutral, hit ignition, starts right up, put back in Drive and go.... Acceleration is fine. Also, check engine is on, and message center tells me urgent, have engine checked, and the little orange triangle with exclamation point on the dash is lit. These lights went out the first two times this happened after restarting. On the third time, lights came on and stayed on. My mileage averaged 24mpg on the trip (about 120 mi.) I did pull off the freeway to check under the hood to see if anything was amiss. Could not see anything obvious like loose wire or vacuum hose. Before I take to dealer, was trying to get idea what is going on.... Car has about 81K mi. on it and had reg service about a month ago. Any ideas? thanks.. marv

Sounds like a faulty brake pedal sensor.

More details here

It might be the fuel control module. My T5 was doing the same thing. I thought it was fuel related. Every time I put Amoco premium in it it would mess up. Since having the module replaced, I have had no problems.
--
Leon Ramseur in NC, 2001 V70XC & 2001 V70T5.

Sounds like you may have the infamous throttle body defect. Get into a dealer fast. If it is the throttle body, the engine will eventually die.

Throttle body builds up a residue as you drive because air is passing through it. When the electronic throttle module (ETM) senses the build-up, it shuts the engine down. Mine shut off on the freeway. When restarted, I could only run about 30 mph. max.

Defect can only be fixed at the dealer or the rare independent that has paid the necessary fees to Volvo. Cost is anywhere from $800.-1,200. depending on the dealer.

If it is the throttle body, the repairs are covered for 7 yr./70,000. mi. for cars built and sold to Calif. and Mass specs. People in other states have to pay.

Hope it isn't the throttle body but I suspect this is your problem.

Edmonds17

(ignore my previous post, something hung when I tried to send it)


It may be something to do with the cruise control and/or vacuum system. It seems to me that if it were either of the previous problems, it wouldn't just happen when using the cruise control, it would happen whenever you accelerated hard.

The cruise control operates off engine vacuum. It sounds to me like it's something that is related to what the cruise control is doing when you hit resume. In terms of accleration, it's no different than pushing on the gas pedal, but it's actuated in a different way.

be something to do with the cruise control and/or vacuum system. It seem to me that if it were either of the previous problems, it wouldn't just happen when using the cruise control, it would happen whenever you accelerated hard.

The cruise control operates off engine vacuum. It sounds to me it's something that is related to what the cruise control is doing when you hit resume. In terms of accleration, it's no different than pushing on the gas pedal, but it's actuated in a different way.

Just an f-y-i, no engine vac or mechanical parts in the cruise Bob. Speed sensors in the abs system for the speed and inputs to the electronic throttle body for throttle control. While everyone here complains about the crappy e-throttle, they overlook all the benefits that come from an e-throttle which include cruise simplicity, emissions management, stability control, etc, etc.

Too bad Volvo picked a crummy supplier and hasn't seen fit to get a new design developed for the previous generation.

Oops, sorry.

Never fiddled with the cruise on it, it's my wife's car.
How come it responds just as jerkily as a vacuum-based cruise control--you think they would have smoothed the response out in software :)

Just out of curiousity, how does the faulty brake sensor produce this kind of response? Does the computer think the brake is still on when you hit "resume" and send conflicting signals to the throttle?

Bob,

I’ve often wondered myself why the software logic for speed maintenance in the cruise is so aggressive. It drives the car to many more downshifts that I do driving manually, and I get about 1 – 2 mpg better mileage than the cruise. I’ve always wanted to have a few moments with the Bosch software people to ask them ‘what were you thinking’ about a few things in the engine / trans / e-throttle software logic and hear their design thoughts. I have a suspicion that if I drove in less rural area with traffic, I might feel differently.

The brake pedal sensor issue is just what you suspect, it is one of the inputs to the cruise logic and turns off the cruise function or stops it from being set to on.