1999 S70 Driveability and Cruise Control - Denso System

NHVolvoNut · Post by **NHVolvoNut** » 18 Mar 2025, 10:42

I have a 85k mile, 1999 S70 5-spd with the Denso system. I currently have a check engine light and inoperable cruise control. In addition, there is a slight but very irritating surge at higher speeds (particularly noticeable at 60-70 MPH) on the highway at VERY light throttle. Engine does not stall or hesitate and idles perfectly. It is throwing a 532D code and a 900E code on Vida. If the codes are cleared with Vida, the cruise will work for a few miles, then drop. Eventually the CEL will return, although it has been going off from time to time, then returning. Cruise does not work when the CEL is off.

XeMODex has had both the ECM and the throttle body twice and can find no issues. It is currently sitting in the shop of a former Volvo Master Tech who was with a dealer during the Denso years and has extensive experience with this system. Tech checked the accelerator pedal sensor on a scope and it passed. The MAF sensor failed on the scope (showed no air flow) but then tested a new MAF and got the same result. Brake pedal position sensor was scoped (and I believe showed as an issue on his Snap-on gear), as it was thought to be the issue with the cruise and failed. A new BPP sensor also failed. He states that grounds have been checked and verified, including the one under the passenger side headlight.

Anyone have any suggestions? This vehicle has NO rust, and I bought it because of previous Volvo experience (V70 and a couple of 244's) and I wanted a 5-speed in something a little better than a base Hyundai Accent. As an alternative, is anyone aware of a Volvo tech with Denso experience and diagnostic equipment in the Central/Southern NH area?

Thanks!

Post by **scot850** » 18 Mar 2025, 17:26

Has the engine pipework been smoked to check for leaks?

Neil.

NHVolvoNut · Post by **NHVolvoNut** » 18 Mar 2025, 17:31

Neil,
Sorry, I'm not sure I understand your terminology. By pipework, are you referring to the intake air tubing?

Thanks,
Graydon

Post by **scot850** » 18 Mar 2025, 17:32

Intake and any vacuum pipes.

Neil.

NHVolvoNut · Post by **NHVolvoNut** » 18 Mar 2025, 17:58

Got it. I'll check with my tech.

Thanks, Neil!

Graydon