Throttle Sensor..maybe more?

[viper69]

I brought my car into the shop for 2 reasons. The check engine light was one, and the cruise control works intermittently. Sometimes it works fine, other times it won't engage, or worse, it will engage, but then stops functioning.

At the stealership, I was told there is no sensor for the cruise control, modern Volvo's have one.

The diagnostics revealed my throttle sensor was out not working, so it was replaced. Read code was 411, not sure if that's internal or from their computer etc.

i drove it for a day, testing cruise control, it worked. Then I noticed sometimes it didn't always work, not to the extent as before, but still a bit inconsistent as to whether it will work or not. When it works, it holds speed at the proper mph, the same was true before it was brought in.

Well, also in the same day, at night what goes off, but another amber Check Engine light- I hate it hah.

This is what I am wondering, and I wouldn't know how to go about this, I'm no mechanic.

Is this a situation where 1 part was replaced, but down the line somewhere because one part was fixed, another part has fallen out of spec according to the onboard computer.

In any event, I will be bringing it back to shop. Not happy.


Last question: Does the LED onboard computer under the hood give out every code? I haven't needed to use it in years, and do not remember how thorough it is in providing detailed information. I DO remember I had to restart the diagnostics because I missed a certain number of blinking lights, that's so annoying, wish there was a way around that.

[scot850]

Sorry I missed replying to your question. Hate to see something not responded to!

Your diagnostic system is a simple tool. It should read most codes that the car can generate on the older systems.

Do you still have the original handbook for the car? If I recall there is a section that tells you how to diagnose from it and what each code is telling you. If not if you google it you can find lists with it on.

Whether you have a stick or auto shift, there is a peddle sensor but I think it is on the brake peddle not the throttle. It is to disable the system when slowing down.

The cruise control uses vacuum and so has pipes to it. It is mounted under the battery tray and is basically a pump if I recall correctly.
The system uses vacuum and pipes that can rot, so check they are all good and connectors to the unit are good.

On a 93 850 GLT we had and leaking battery acid had actually run through the tray and eaten through the casing which prevented the pump working. Like any old mechanical thing, it is maybe intermittent.

Neil.

[viper69]

Sorry I missed replying to your question. Hate to see something not responded to!

Your diagnostic system is a simple tool. It should read most codes that the car can generate on the older systems.

Do you still have the original handbook for the car? If I recall there is a section that tells you how to diagnose from it and what each code is telling you. If not if you google it you can find lists with it on.

Whether you have a stick or auto shift, there is a peddle sensor but I think it is on the brake peddle not the throttle. It is to disable the system when slowing down.

The cruise control uses vacuum and so has pipes to it. It is mounted under the battery tray and is basically a pump if I recall correctly.
The system uses vacuum and pipes that can rot, so check they are all good and connectors to the unit are good.

On a 93 850 GLT we had and leaking battery acid had actually run through the tray and eaten through the casing which prevented the pump working. Like any old mechanical thing, it is maybe intermittent.

Neil.

thanks!!

I have a PDF file that contains all the codes. I will dig it out. I wasn't sure if the on board computer w/LED lights would display all the codes. I obtained the PDF file from this site Saved it!

The only thing I'm aware of is from the original manual (single owner car, just me), when the cruise control is engaged, if you lightly touch the clutch it disengages the cruise control.

Uses vacuumen, man I have no idea how this works then hah.

I will have to find a picture of this vac/pipes, I am not sure I'd recognize it if I saw it to be honest.

I used the cruise control yesterday, and it bounces around a bit I saw. If set for 60, it may drop to 55, and then go back to 60-62 at times. Never noticed that before, but I havent been able to use cruise con. for eons regularly. The change in speed seemed to vary when the road was not level. I have a newer car that doesn't do this on the same road. It's from the early 2000s, non Volvo

[scot850]

You will need to wait and I hope an 850 owner will chip in on how well the car holds speed. It has been too long since I drove one, but don't recall any issues other than when going up hills it would loose speed before changing down and getting back to speed. But that is on an auto. To be honest, don't think I have ever used a cruise control on manual trans so not sure how that copes with this copes with inclines.

Good Luck!

Neil.