When I bought my car, someone had rigged the fan to turn on by connecting a wire to the battery, and I tested it and the fan works, so I know the fan isn't the actual problem.

My question is, what makes the fan turn on automatically other than the a/c?

Where is the sensor/switch/thermostat and relay that makes it turn on?

Also, what are the three sensors on front of the radiator on the bottom passenger side? They are 3 different colors, I can't find any information on them.

As always, any help is appreciated and thanks in advance!

-Dillon

 

From memory, the electric fan sensor is on the back of the right side of the radiator, about 2/3rds of the way up, but let me verify this from the greenbook diagrams....

ok, no, its a bit more complex.

pressurestat 7/38 is used on LH2.4 or regina systems, its the grey sensor in the middle of that manifold at the lower right of the condensor, this enables low speed fan operation.

pressurestat 7/40 is the brown one in the middle of that manifold, it controls high speed fan.

on a regina system, thermostat 7/14 is on the upper right side of the radiator, and it ALSO controls high speed fan.

the ECU can also force either low or high speed fan operation.

all of these things provide the ground paths for the fan relay coil circuits. this is wired as an "OR" function, eg, either 7/38 or the ECU can enable low speed. either 7/40 or 7/14 or ECU can enable high speed.

is that clear as mud yet?

 

Ok I think I pretty much understand haha.

Could the thermostat be stuck not allowing the hot water to get back to those sensors or is that possible? I don't see it possible that both sensors went out because my fan doesn't turn on high or low, ya know?

Could my ecu just be gone or is there a relay for the fan also and could this just be the problem?

Also, another problem while I have your attention.

When I start the car it idles very low, like it barely registers any rpms, and all of my warning lights stay on at the bottom of the instrument panel. When I rev the car up it revs smooth (the speedometer also started going up to like 20 or 30 mph while I'm sitting completely still) the lights go off and it sounds really good honestly. When I let off the gas it goes back to idling low and the lights come back on. They intermittently go on and off when revved up too. But when the car gets warm, it idles around 2000 to 2500 rpms, and the lights are off. Then (with the fan hotwired to the battery the whole time) the car overheats within 5 minutes or so, and I turn it off quickly. What could be causing all of these problems???

 

Ohh, also when the car is warm I put the car in gear and it idles low and almost dies too...

 

staying with the fan thing for now... the fan itself is run by a double-relay, which is more or less behind/below one of the headlights, right for a non-turbo, left for a turbo. the relay has 3 connectors, if you face the side of the relay away from the mounting clips with the connectors on the bottom, the rightmost connector is 'A', the middle is 'B', and the left is 'C'

first, verify that there is power on relay pin 1A (red wire). this is always-on power direct from the battery via an inline fusable link. if there's no power, follow the wire back to the battery, find the inline fuse.

next, unplug the relay. use a heavy jumper wire to connect pin 1C (green) to pin 1A, the fan should come on LOW speed. use the same jumper wire to connect 2C (red) to 1A (red), and the fan should come on HIGH speed. if the motor doesn't work, its a dead motor (or maybe its ground wire or connection is bad?)

now, plug the relay A and C back in, leave B unplugged. on the relay side (not the plugs), use a jumper wire to ground pin 1B (thats blue-black on the plug side), the fan should come on low. ground pin 2B (white-black on the plug side), and the fan should come on high. if the first two tests were good and this fails, its a bad fan relay.


your idle problem, eek. that could be a lot of things. if the speedo is reading when the car is stopped, it sounds like there's a grounding issue under the dashboard. the overheating, is the radiator top main hose getting hot once the car starts to warm up? I do believe I'd take a volt meter, put one probe on the battery negative post (the actual post, not just the clamp) and when the engine is running, measure the voltage offset at various places that /should/ be ground, like the fuel injection rail where the brown ground wires are connected, the metal body of the alternator, and so forth. anything more than a tiny fraction of a volt suggests a ground problem.

because you have multiple symptoms that ALL /could/ be ground related, my first suspect would be the main battery ground cable.

 

Well all of the tests were fine so I started digging through wires just for fun and apparently whoever put this replacement radiator in never put the fan switch back in the new radiator...

And I'm about to check out grounds now and yes when it runs hot the top hose is warm and the lower hose is only warm about an inch from the water pump but the rest of the hose is cold

 

Also where is the fan switch supposed to go?

 

the pressurestats are in the AC condensor manifold, they measure the AC coolant pressure.

per the 1993 wiring diagrams, only regina equipped cars have a temperature sensor in the radiator. I've never seen a Regina system, apparently they were never shipped to California. If your car has Regina, it will NOT have a Bosch MAF/AMM in the air intake path, instead it has a MAP (manifold air pressure) sensor. if your car is a turbo, it will be Bosch.

hmm. so the radiator itself isn't getting hot ? sounds like a bad water pump. or a clogged radiator.

 

Yes sir, my car is non turbo with regina. And I'm starting to think that someone installed the wrong radiator because this radiator doesn't have a spot where I think the temp sensor is supposed to go. I wonder if theres any way to retro fit this sensor in that radiator? I really would hate to have to buy a new one because the one thats in there is brand new itself...This is why I don't take my car to mechanics...

Anyways, would the MAP make the car run rough like it is?

And I lied to you on accident, the top hose isn't getting hot when the car overheats, heck neiter of them are honestly, so that means bad thermostat right?

 

What it looks like it someone put a turbo radiator in a non turbo car.... The first picture is what it is supposed to look like, notice the top right of the radiator has a spot made for the temp sensor to go in. The second picture is what the one I have looks like, notice it doens't have the spot on the right...

Could I drill a hole in the radiator I have and seal the sensor in there real good with some jb weld?

 

either a bad thermostat, or a bad water pump.


re: the radiator, I believe the temp sensor goes in that stub thats capped with the hoseclamp on your 2nd pic. the brass looking connectors are for the transmission cooler, the big one is for the main radiator hose, and the little one sticking out sideways on the far right side is for the overflow bottle ... those two pictures appear to be two completely different radiators. 1992+ 7/9's use a different larger radiator than -1991.

 

Alright, I'll probably replace the thermostat first just because its cheaper haha.

Well that one thats capped with hose clamp is where the overflow bottle goes back into the radiator and is how you fill the radiator up, and it may be different, I was just posting them so you could get a mental idea of what I was talking about forreal.

 

this is a radiator (shown kinda upside down) for a 1992+ non-turbo 940, see the fitting to the right of the rightmost brass transmission cooler fitting? thats where the sensor goes. the little barb below it is the return line from the overflow bottle.



(and, you're right, that middle fitting with the clamp in your pic is the main line to the oflow bottle, oops)

 

Well dang....How bad of an idea would it be to try and make the sensor fit in that radiator? Like drill a whole the size of the sensor, put the sensor in there with some silicon to seal it up good, let the silicon set and then use jb weld to seal it up even better and make it where it doesn't come out? Think it'll work? even if it doesn't work and I mess up the radiator, I would've had to buy a new one anyway ya know?

 

or I wonder if I could do something like this?

 

You could. That looks pretty good!

 

For now its wired to the ignition and runs constantly on low but I've got a switch for high. I took the thermostat out just to see if that was making it run hot and with the thermostat out it doesn't run hot at all, runs lower than its supposed to, of course, which means that my water pump is fine right?

And its got a hesitation when I try to take off, so I reset the old obd codes and seen what new ones came back up.

Plug 2 I'm getting, 1-2-3 still(even after I just replaced the ECT), 1-3-2, and 1-2-2
So, faulty wiring or ECT sensor, faulty signal fromair temp sensor, and my battery is low, got it on charge now haha

Plug 6 I'm getting 1-4-3, knock sensor signal fault how can I check and fix this?
and 2-2-4(again still don't know why this code keeps popping up)

 

A lot of these OBD1 codes are unreliable. I don't pay much attention to them as long as the car is running well. Your pump seems fine.

 

i'd check the ECT resistance at the connector to the ECU with an ohm meter. if its way out of range, then check it at the ECT itself, too, as it could as easily be a wiring harness problem as a bad ECT. See this Engine Sensors for the resistance values at various temperatures. The ECT is pin 13 of the plug into the ECU, and. ground is pin 5 of said plug.


for the test at the ECU, I would get the engine hot first, then check it, then wait for the engine to cool down, and check it again.

I dunno anything about air temp sensors, Bosch cars don't have those.

 

Yeah lev, I mean I wouldn't worry, but it has a hesitation when I accelerate, and when its idling it kind of sounds like its skipping, running on 3 cylinders ya know? Plus my check engine light popped back up and I don't like seeing that haha... I'm going to check out the knock sensor when I get off work too, and clean it up and check its wiring and see if it helps any..

I'll check of that when I get off of work today pierce, also how do I get to the ICU to check it? I never could figure out