Turn signals not flashing properly

2000 JEEP GRAND CHEROKEE

116,000 MILES • 4.0L • 6 CYL • 4WD • AUTOMATIC

JORDAN MCGUIRE

MEMBER
3 POSTS

I’ve recently replaced both headlight assemblies and everything is working fine but when I turn on the turn signals they don’t just do the one flash as normal. They do a double flash back and forth like an emergency vehicle or something weird on the front bottom of the lens.
When I first got it I had to replace the turn signal relay under the dash to get everything working correctly and it worked. They are also all new bulbs

Mar 18, 2021 at 11:15 AM

KASEKENNY

✓Experienced Mechanic
18,907 POSTS

Okay. Couple questions. First, did you install LED bulbs in any of the assemblies? If so, let's try and put the OEM bulbs in there and make sure it does it with those as well.

LED bulbs have very low resistance and that throws off the control module and causes these types of strange issues.

Also, did this start after the assemblies where replaced? Does this happen on both turn signals? Meaning if you turn the left or right it causes this issue? Also, do the front and rear turn signals flash this way?

Let's start with this info and we can go from there. Thanks

Mar 29, 2021 at 5:24 AM

JORDAN MCGUIRE

MEMBER
3 POSTS

No LED installed, just regular bulbs. It started when the new assemblies were installed and happens on both left and right. The rear signals operate just fine.
(All new bulbs front and rear)
Nothing changed with the new assemblies, it’s just snapping the bulbs and holders into the new assemblies and locking them in by turning them like all others and not changing anything. I don’t know what could’ve happened.

Mar 29, 2021 at 5:24 AM

KASEKENNY

✓Experienced Mechanic
18,907 POSTS

That is very strange as you are correct the assemblies should have nothing to do with it. Do you still have the old ones? I can't imagine it would matter but it worth trying to just hold the old ones close and click the sockets with the current bulbs just to see it is in fact the assemblies or rule them out and confirm our thinking that it can't be them.

Also, do you have the part number and who makes the assemblies?

Mar 29, 2021 at 5:24 AM

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