3/2 wire tail light converters ???

A buddy had his car painted and now the turn signals won't work. It has a UHAUL 3 to 2 wire tail light converter wired in so he can use a single 1157 bulb in each tail light. I checked the unit and it is recieving voltage from the headlight switch ok, the brake light switch ok and the turn signal switch ok. But there is no voltage out to the brake/turn wires feeding the rear lights. I tried 4 different new converters, triple checked all connections and grounds and jumper wired all lights to check continuity. Everything checks out fine except the converter units will not pass a signal to the tail lights. Everything worked perfect before it went to the paint shop. What am I missing ??????
Any help or ideas would be greatly appreciated.

BTW this is how it's wired http://www.how-to-build-hotrods.com/images/turnsignal07.jpg

 

Your converter needs to be grounded too! It should have a white wire (or the opposite sex terminal from the other three terminals on the 4 flat connector) that needs to be grounded. Your diagram does not show a ground for the converter. Take it from me, I work for a company that makes the converters.

 

It's grounded. I robbed that schematic from the web because it showed the same basic layout as the car I'm working on. The converters I'm useing all have grounds (in and out).
I have them both grounded to the same terminal on the chassis. Does the converter need a load on the output side before it will pass a current ?

 

some of them do..... make sure the taillite housing is grounded if they pulled them when they painted.

 

Got good grounds on all the lights. I can bypass the converter with a jumper wire and work the lights individually but none of the converters (the original or replacements) will pass a current. One thing that is wierd is that with the original UHAUL 17157 converter, the dash indicators will blink when triggered (but no turn signals) but the replacements (Hoppys) won't even blink the indicators.
The indicators are pea lamps hardwired to the output terminals of the turn switch.

 

Also, the taillight bulbs are 12v 1157 and the front bulbs are the small orange wedge based 12v type used in most side marker lights.