Vehicle circuit detection diagnosis device

The utility model relates to a circuit detector, specifically a vehicle circuit detecting and diagnosing device in vehicle servicing field. The technical proposal is as follows. A power supply voltage detecting circuit comprises a switch K1, resistances (R1, R2) and luminous diodes (D1, D2). An audio frequency oscillation circuit comprises a switch K2, resistances (R3, R4), a time base circuit IC, capacitors (C1, C2), a loudspeaker L and a power supply DC. The two portions of the circuit are connected with contact pins (T1, T2) to form the vehicle circuit detecting and diagnosing device, wherein, the luminous diodes (D1, D2) are of pole reversal and the switches K1, K2 are coupled switches. The vehicle circuit detecting and diagnosing device achieves simple structure and convenient use and can conveniently detect the existence of the power supply only with the listening of the circuit on- off detection compared with the multimeter.