Jeep: jeep turnsignal, jeep grand cherokee, turn signal switch

Question
i have a 99 jeep grand cherokee the left turn signal does not click or light up when it is activated and the lights dont flash outside they do work on the right side and the hazard lights function properly all around the car even the left side. i checked the turn signal switch with a multimeter and it is working properly. i want to know if it is the turnsignal relay or is there a way to test it because i think it is a dealer only part

Answer
Hi Ed,

Normally, with this type of problem, or anything electrical, the first step is service information (schematics, locations, diagnostics, etc.). However, I'm almost ashamed to say that the factory service manuals' diagnostic for the Combination Flasher is "replace it with a known, good unit". Ugh. Great.. and this from the manufacturer. Still, a schematic is mandatory, to avoid a guessing game. That said, I have *some* info that's useful.

First, the Combination Flasher is in the front Junction Block, below the IP (under and to the left of the steering wheel). It's in the center, top position, opposite of the mini-fuses, and looks similar to the relays there (it's really just a smart relay). In the service manual, they often don't describe the logic in the 'magic boxes', so we just determine functionality by input and output. There should be at least 1 terminal, possibly 2 (cavity #1 and #6), with B+ (12 volts) when removed with the key ON. If that's good, then test the voltage at various outputs (bulb sockets) to determine proper output. The part number is 4686 094 (this should match yours), and they have been known to fail before.

I can't stress enough that these problems are often at the bulbs -- double check all bulbs, as these can be overlooked at times. Also, we've had a number of issues with the multi-function (turn signal switch), and the fact that these Combination Flashers have 'sense lines' from the T/S switch is often confusing. Check for continuity between ground and terminal 8 (LB/WH wire -- at the switch) to see if the T/S switch left switch is working properly. Then check for continuity between T/S switch terminal 8 (harness side) and and Combination Flasher terminal 7 (again the LB/WH wire).

Good luck!