Was driving on the local freeway, about 70 mph, cruising, and my TURBO indicator came on all by itself. Pressed the button to turn it off, and it stayed on for about 5 miles (with me alternately pressing the button, thinking it might turn off one of these times). I finally pulled off the Beltway and the turbo indicator went off. So, I get some gas, get back on the highway, drive about three miles and it comes on again. By the time I got home, just as I pulled into my parking space, the TURBO light went off again.

Anybody got any ideas what caused it to suddenly come on by itself?

"Pressed the button to turn it off, and it stayed on for about 5 miles (with me alternately pressing the button, thinking it might turn off one of these times)."

Are you referring to the button on the side of the shifter? The overdrive light is an orange/amber arrow that points upward. The indicator illuminates when you have locked out overdrive via the pushbutton on the shifter, or when the overdrive relay has failed and prevents the car from shifting into OD.

The 240 turbos had a "TURBO" idiot light in the instrument cluster, but late model 740/940 turbos that I have seen do not (someone else asked what year your car is). IIRC, the "turbo" light means that there is something amiss with the turbocharger or ancillaries. Could mean that the turbo is overboosting which can be fatal under hard acceleration. Check the actuator hose at the wastegate. If it is split or simply not there, the wastegate will not open.

What does the turbo light look like?
--
Jim McDonald

86 Volvo Turbo wagon. "Turbo light" is newbie-speak, describing the the orange/yellow arrow on the "idiot lights" that points upwards. It comes on when I press (what I thought was) the TURBO button on the left side of the shifter.

So that you know, the overdrive relay is behind the ashtray. Pull out the ashtray, take out the cigarette lighter, pull the face clip off of where the lighter resides, exposing two philips screws, take them out, pull out that panel, and viola, you can see your relays (at least some of them). The tall white rectangle on the RS is your overdrive relay...this is the culprit. Some people on this board solder theirs, I generally replace 'em.

So you know...several customers have said, "I never use my turbo" which starts a discussion about it's exhaust driven, as you as you are creating exhaust, the turbo is working...no, I NEVER press the button on the gearshift...

One customer of mine, with a 1987 Volvo was heading to his in-laws for Christmas and requested quite a bit of service before heading that way. He called to say, "Wow, the car did great! Since it has been so long since I had service I never used my turbo...man, I hit my turbo button at 75 mph and you should have heard that baby scream!" "Scott, your car doesn't have a turbo. What do you mean you hit the button." "You know, Chris, the one on the gearshift." "Scott, NEVER DO THAT AGAIN."

Welcome to the world of Volvo...you'll like it here.

Chris

SO what exactly did i do when I pressed the overdrive button (thinking I was selecting turbo -- that made the car respond with a burst of power)?

You were turning overdrive off...you have a three speed transmission with automatic overdrive (so, basically a four speed transmission). By turning off the overdrive, you downshifted into third gear. It's a little hard on the car at higher speeds.

Well, well, well . . . the 1986 Volvo manual that I ordered off of ebay arrived today, and sure enough what you say about the overdrive selector is absolutely correct. But, man, this thing sure took off when I pressed the [fantasized] "turbo button". I blew past an 18 wheeler like I was driving a Porsche. This manual is really helpful. I had no idea I could drop the middle seats for more room, even take the cushions out if necessary, found I had a tool kit hidden in here (completely stocked, even had a glove in it that had never been used -- nice touch). I really like driving this car. Gonna get the windows tinted this weekend, so nobody will know who it is who is still playing with their overdrive release as though it is a turbo boost button [smile]. Thanks for the advise, and I don't mind the ribbing at all.

We fashioned a little "turbo" sticker, and put it on Scott's gearshift the next time he was in for service. He left it there...and it stayed there...and would probably still be there today...if he hadn't caught his car on fire...but that's another story, and in no way related to the "turbo" button.

"We fashioned a little "turbo" sticker, and put it on Scott's gearshift the next time he was in for service. He left it there...and it stayed there...and would probably still be there today...if he hadn't caught his car on fire...but that's another story, and in no way related to the "turbo" button."

HA! Great. Er, got any more "turbo" stickers? I'll pay shipping and handling. Actually, I was thinking of convincing myself that this was one of Volvo's "undocumented features", open my sunroof, and click that "turbo" button when I really need a quick boost and let it go with that. (;

We just cut out the "turbo" part on a windshield sticker that used to advise turbo owners to warm up and idle down, made it darker with a fine tip permanant sharpie, and stuck it on with 3M clear adhesive. With the advent of every kind of label known to God and man for the printers that everyone has, you should be able to make one with ease...and it'd probably look alot better than that one we fashioned (wow) almost ten years ago.

"Well, well, well . . . the 1986 Volvo manual that I ordered off of ebay arrived today, and sure enough what you say about the overdrive selector is absolutely correct. But, man, this thing sure took off when I pressed the [fantasized] "turbo button". I blew past an 18 wheeler like I was driving a Porsche."

When you lockout the overdrive, you force the transmission into 3rd gear. The engine is now running at a higher rpm at which it develops more torque than it does at the same speed in overdrive. Rather like downshifting a manual transmission. I see no harm in using the overdrive lockout in this fashion when climbing a grade or for passing another vehicle. These engines like to rev, and as you know the turbos pack an impressive punch over 3500rpm.

Oh dear, sorry but this is funny. You thought that the button on the side of the shifter switches the Turbocharger on? Dear me, sorry, but I cannot stop laughing. No offence mate, but you are mistaken. That is the button for the overdrive on the gearbox. You have an electrical fault on the overdrive. Check the FAQ for starters.
--
George Holmer, Belgium, Europe, 1995 940 Turbo; 1987 745 GLE Turbo Diesel; 1979 262C Intercoolerhttp://www.ttsservices.co.uk/my%20volvos.htm

what year? chuck.