2005 saturn vue 4c. 5sp. code PO378 is on,there"s is no timing on these car so is it the timing chain ?

Code P0378 means, DTC P0378 Timing Reference High Resolution Signal B Intermittent/Erratic Pulses. DTC stands for Diagnostic Trouble Code. I highly doubt it has anything to do with the actual timing of the engine. Chances are there is a problem with the camshaft / crankshaft sensor (which measure engine timing). Without a scanner that shows individual sensor inputs there's no real way to know. I would try replacing the sensors (they aren't incredibly expensive), this should take care of the problem and if not the only other option is to take it into a repair facility.