Diagnosing Dead Turn Signals on 2003 Itasca Sunova Workhorse Chassis

[wright8way]

First trip in our new to us Sunova MH. Its a 2003 Itasca P-32 GM workhorse chassis and has 36,000 miles on it and has been beautifully maintained. Mid trip the turn signals stopped working (sporadically), then completely. Fuse is good, 4 way hazards are good, turn relay replaced to no avail, and cruise control works fine. I have 12 volts to the blinker relay with key on at pink wire, but no power through relay in either right or left position. Is there anyway to test the multi function switch in situ or to prove where the problem lies? Is there any other relay in the circuit I might be missing? Anyone's help on this would be greatly appriciated.

 

[uchu]

Welcome to the forum.

The troubleshooting that you've done so far leads me to believe that the problem is the multifunction switch. I am not sure how to test it specifically for the signal turning function, though.

 

[Mark_K5LXP]

"Blinker relay" - you mean the flasher? (there is no relay there). I do see a pink wire as 12V input to the flasher on the schematic. That comes from the ignition switch.

"No power through the relay" could be a clue - flasher units operate as current interrupters, not current sources. Meaning, I would expect to see 12V at the output of the flasher if there's no load (turn signal switch open). My first test would be to jump across that flasher which would make the blinker lamps illuminate fully left or right with the turn signal switch. Or if the hazard flasher has the same pinout, try it in the blinker position and see if that operates.

Mark B.
Albuquerque, NM

 

[TheBar]

Don't forget the left and right mechanical switches inside the steering column could be dirty or corroded.

 

[BillyThib]

Retired Workhorse technician here, If you have access to a wiring diagram determine which wire supplies the turn circuit at the switch. Measure ( not a test light) the voltage potential at that wire and activate the turn signals, the reading should remain constant with minimal fluctuations as the lamps blink, which they don’t so, if it goes low then there is a high resistance between the power source and the switch. Remove the flasher and jump it with a short wire male spade connectors, operate the switch, if the turn signal lights illuminate the problem is the flasher. IN FACT, TRY THAT FIRST!!! Since the problem was intermittent before totally failing, this would be more likely than any catastrophic failure downline.

I still have access to the system diagrams if you need further assistance.

Finally, the Workhorse to Body Builder connector could be another problem area and typically is located behind the instrument cluster.

Good Luck
Billy