QuestionQUESTION: Where is the OAT sensor? I'm good with a VOM, understand sensors that vary resistance as a way to vary voltage back to a gage, if this is the type sensor this is. One of your earlier posts tells m e where to go look for what wire in the B pillar connector, but I'm just starting to T/S this problem and want to know where you would start.
ANSWER: Hi Lee,
OAT means outside air temp sensor,and shows O C must mean the readout shows 0 degrees centigrade, correct?
The sensor is located on the front side of the radiator closure panel. The drawing is a bit 'opaque' to me, but I picture this to be a panel that is to the right of the radiator proper.
It states that to access it you need to lift the van, go from underneath to find the panel behind the bumper fascia, and you would find the sensor held on the panel by a screw loacted near the lower edge of the panel. The twisted pair of wires (black/light blue is sensor ground, violet/light green is sensor signal) are routed over the wheel well of the right fender and down along the floor in the cabin to the base of the B-pillar where there is a red 6-pin disconnect which couples the wires to a harness that goes to the roof and then into the overhead console. You would find the other ends of the wires at pins 2 and 5 of the overhead console. You can open the disconnect as well to check the wires there on pins 2 and 4, respectively. It is a temperature dependent resistor involved in the sensor. The 0 degree reading means the signal wire (violet/light green) is shorted to ground some where between the sensor and the console or perhaps in the sensor itself.
Roland
PS Please 'rate' my answer, and where you see the question about a nomination of me to be 'volunteer of the month consider a 'yes' answer. Thank you.
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QUESTION: Hi Roland,
Thanks for theinfo. I took a quick peek when the wife came home with the van, and I see in the area you siggested most obvious what looks to be the windshield washer pump and reservior sensor connectors. Can you tell me where the OAT sensor lives in relation to these connectors? THere was a 2-pin connector not connectoed to anything, but the wire colors were not what we are looking for.
Second question, do oyu know waht signal the O.C. is looking for from the sensor? Is it a voltage or is it a variable resistance? I ask, as if I can go to the O.C. and apply a potentiometer of the proper range to the connector pins 2 and 5 to verify the O.C. works as advertised.
Third question: If I go to O.C. connector and measure pins 2 and 5 each to ground, should I see one of them as grounded, if the wires are intact? Which is the black/lt blue gnd? 2 or 5?
ANSWER: Hi Lee,
The drawing is puzzling in that it seems to be a mirror image and partial, so if I read it that way then what the sensor location may actually be over on the left side closure panel, via the harness which indeed passes by the area with the washer pump/reservoir and then crosses over on the lower edge of the panel to a spot on the left closure as the mounting location of the sensor. So see if that is the case.
While the internal console circuit is not described in detail, the sensor is a variable resistor, so the circuit evidentally measures current flow which would decrease as the resistance increases. The black/light blue is described as 'sensor ground' on pin 2 of the console, and the violet/light green is the atc (or oat) 'sensor signal' wire on pin 5. So in any case you should see a specific resistance across the sensor pins, and that same resistance should be seen between the two wires at the disconnect, and at the console all measured with the plug removed at the console. And the resistance should change as you heat/cool the sensor. If that is true and yet when you plug it in to the console it reads 0 C. then I would believe the problem is the console. "Sensor ground" may in fact also be the same potential as "chassis ground" but "clean" in the sense of not having to carry return current to the battery from other components in the car. The manual says that if the circuit is open then the reading will be '0 C.' while if the sensor wire is shorted to ground it will read 'SC'.
Roland
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QUESTION: OK, lots of stuff under the left front of the van, but nothing apaprent with those color wires. So lets go at this another way.
1. What does the sensor look like?
2. I'm going to measure the circuit at the OC. I found one screw in the aft compartment of the O.C., but it is not obvious how the console comes down as removing the screw makes the whole thing loose, but the front is still held up by somehting I cannot see. How does the OC come down? I'm going to go to pins 2 & 5 and see what they say now. If I get an open on 2&5, or open 2-gnd, then I know to renew my search for the OAT sensor, as the most likely open is a bad sensor or a broken wire under the car. You agree?
AnswerFollow-up answer:
Hi Lee,
Thanks for the report on the specific location of the sensor. To be clear, there are three panels involved from what the manual shows: the front bumper fascia (which you called the 'dam', and the metal front bumper reinforcement to which it attaches, and then there is apparently a thinner metal panel that surrounds the radiator on its sides and across the center underneath it called the 'closure panel'. In later model years they put the sensor on the reinforcement. Is that what you would say too it where you found it to be attached, or was it to the closure panel?
Roland
Are you looking on the Front side of the radiator closure panel? I doubt there would be much on that side of it, so it ought to be visible, but then I can't say I have seen it in person. I suspect it is a very small device. Do you see any 2 wire harnesses over on the right side as it appears to be the only such line that would then run across from right to left.
To remove the console:
open the transmitter bin door
remove the screw holding the module to the headliner
there is an engagement tab inside the eyeglass bin that holds the module in place still
open the bin door
press the tab located above the door latch
lower rear of console from headliner
pull console rearward to disengage clips holding front of console to roof armature, lower console
then disconnect plugs making sure to lift locking tab of each before pulling on them.
