Speedlite 430EX II & Speedlite 600EX-RT underexposed.

[rrnkp]

Hi,   I have 430 EXII and a 600 EX. On my t6i both flashes set to E TTL  work properly in all modes  auto, program and manual, with the exception of the exposure confirmation lite on the 600 EX. It does not illuminate.

Now the weird part when I use either flash,E TtTL, on the the 70d both flash are under exposing but the exposure confirmation light flashes on the 600 EX, meaning it was properly exposed. Either I have to go +3 on exposure compensation or manual 1/1 for the pics to come out properly. This occurs in all modes auto, program and manual.

I'm photographing dimly lit parking lots/ streets at all distances. Both cameras have 18-135 Canon lens. 
I’ve tried the Canon 18-55 and 50mm f1.8 on the 70d still under exposed.  
 Any ideas on what’s going on?

[Anonymous]

Make sure that in the 70D external flash menu that wireless flash is disabled.

Also make sure that the ETTL II metering mode is set to Evaluative instead of Average in the camera flash settings. These settings are not available in the camera auto shooting modes.

Is the camera hot shoe in good condition and not loose or dirty?