Chrysler Repair: 03 Grand Caravan cooling fan relay, amp fuse, pin sockets

Question
Hey Roland
My '03 Grand Caravan has a constant engine light showing. I checked the codes and it shows a cooling fan circuit or relay code. I checked the fuses and the 40A was blown. I replaced the fuse turned on the AC and the fan still won't come on. Also on a few occasions when I turn on the wipers all the gauges go crazy - peg and then go down to nothing - then it looks as if the vehicle is restarting, etc. It has always run fine while going through this process but it can't be good. Is there a good way to know if the problem lies with the relay? fan?
Thanks for your time and expertise

Javan

Answer
Hi Javan,
I would check the fuse again with a testor or at least look carefully for a subtle crack in the wire. If it tests o.k. I would try the test the fans with the jumper directly from the battery and also of course a ground for the black wire.
If that all check out, then I would pull the relay and jumper it crosswise in all 4 directions (+ to one terminal, -to the opposite terminal, reverse polarity and retry) until you get it to click. Then while it is in the clicked (closed) position check for continuity across the pins in the other direction using an ohmmeter or continuity checker to see if the contacts in the relay are conducting or not. If not, buy a new relay.  Finally, check to see that you are getting 12v on one or the other of those two internal switch pin sockets at the relay socket which should be there, arriving from the 40 amp fuse via a gray wire.
In theory if the fans work, the relay works, the current is arriving at the relay then the only reason the fans won't operate is because the grounding signal to the relay from the engine controller is not closing the relay switch. That signal arrives on a light green/dark blue wire from the controller (but I don't know the plug or pin assignment to look for it at the controller end of the wire).
Let me know what happens.
Roland

Reply:
'03 Grand Caravan cooling fan relay 1/17/06 I had checked the 40A fuse after replacing it and testing the fans - the fuse is still good so should I still try to jumper the fans or should I look elsewhere? Thanks again jmorris@crweng.com


Hi Javan,
I would look at the 40 amp fuse again to see whether it blew. If so, then I would disconnect the fan motors at their nearby connectors and jump 12V directly from the battery to the motor via the connector pin that usually is connected to the dark green wire that comes from the relay, but if there is a two-pin connector then I would also ground the wire that is normally connected to a black wire at the connector if there is one (I don't know whether it is a 2-wire or a 1-wire conector to each fan with a separate ground wire.). Just tap the jumper to the + post of the battery to see if each fan runs or not. One of the fans may be shorted to ground which will blow the 40 amp fuse. If the fans work, then the gray wire from the fuse socket to the relay should be checked with an ohmmeter for a short to ground, and check the dark green wire when it is disconnected both at the relay and the motors for a short. If no shorts are found then check the relay for a short to ground.
On the gauge/wiper intermittant behavior, I don't have the complete wiring diagrams for the '03 so I can't conjecture on the reason for that problem. 'Sorry to not have that capability.
Roland