looking for 1988 delco radio diagram

[endresp]

hey everyone I have a chevy c1500 silverado I am looking for the schematic for the delco radio model 16072800 the three pice unit . the issue I have is it sounds like a bad ground hum when i turn the unit on . I have tired two diffrent display units and keeping the tape player unhooked same everytime. the thing i notice while trying to trouble shoot is the the left audio ground on the unit is tersting as an open pin number 11. I appreciate any help thank you

[nickeliah1]

Did you work this out? I'm having a similar issue https://www.gm-trucks.com/forums/topic/253124-engine-noise-on-radio-1989-c3500/