Companies developing autonomous and connected-vehicle technology are bumping into an old problem concerning electronics: interference from other wireless devices.

These signals, referred to as electromagnetic interference, go back to the early days of radio technology and can significantly impact the operation of computer chips. Researchers now are attempting to isolate the problem for connected vehicles.

“Think about all the radios reporting out there; you’ve got some really significant issues,” said Rahul Razdan, a researcher at Florida Polytechnic University who has worked in the connected-car space.

The problem for connected vehicles was thrown into sharp relief when Intel’s Mobileye autonomous tech subsidiary began testing in Jerusalem in May, only to have a prototype autonomous vehicle run a red light during press demonstrations.

Mobileye CEO Amnon Shashua pointed to wireless signalsfrom a local TV station’s cameras, saying they disrupted the traffic light’s transponder, which sends information to vehicles on signal changes.

“It was a very unique situation,” Shashua told Bloomberg News. “We’d never anticipated something like this.”

But several carmakers have faced electromagnetic interference for a bevy of technologies, from wireless phone charging in the car to electronically controlled steering and braking systems.

Identifying problem areas can be challenging. As cars become more computerized and connected, engineers could have trouble discerning the source of interference. Multiple overlapping wireless technologies complicate the challenge.

Federal Communications Commission regulators attempted to pre-empt the issue over a decade ago by setting aside the 5.9 GHz spectrum exclusively for car-safety applications via dedicated short-range communications. In recent years, advocates of competing cellular-based connected-car technologies and niche robotics firms have called for sharing the spectrum, causing uncertainty for engineers working to address radio interference.

Problems arising from interference would be especially acute in city centers, where some companies expect the first deployments of high-level self-driving cars to occur. Waymo, General Motors’ Cruise and Uber Technologies all plan autonomous ride-hailing services. Many test centers are being built in remote areas where radio interference can be controlled.