Coolant temp sending unit... wrong one on my car?

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DangerWillRbnsn
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Coolant temp sending unit... wrong one on my car?

Post by DangerWillRbnsn »

HI fellas. I've got an '87 535is. The temp gauge is all over the place, and bugging me. I never know if I'm overheating for sure or not. Anyhow, I'm on a mission to fix it. I've purchased a new Programa battery-less SI board, and it's better but not right still.

Today, I have been Running searches through Pelicanparts, bavauto, and autohaus, I'm getting some mixed ideas on what coolant sending unit I should order.

Apparently, my car SHOULD have a two-prong temperature sending unit, part number 62-16-1-360-870-M323 from pelican.
Image

Instead, what is currently installed is a single-prong sending unit, as found on the 533i, and 528e (part number 62-11-0-788-115-M323 from Pelican).
Image


The wiring on my car has the two brown wires terminating into a single female spade connector, and plugged into the 62-11-0-788-115-M323 sender. It looks like it is correct as it sits in the car, no hacking by the P.O. But I wonder why there are two wires to it? Maybe I should order the two-wire sender and split the two wires and crimp on a pair of female spades?

Any input before I order parts and/or cut and splice the harness?

TIA,
DWR
Image
RonW
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Post by RonW »

Your car has a coolant temperature sender and a coolant temperature sensor.

Coolant Temperature Sender: One spade connector. This goes to the temperature gauge and pin 4 on the diagnostic connector. This is right next to the upper radiator hose, on the left side of the car, i.e. your right, as you're standing over the front of the car staring at the engine.

Coolant Temperature Sensor: Two-pin connector. This goes to the ECU. This is a few inches away from the sender, toward the valve cover.

(The thing between the sender and the sensor is the thermo-time switch, used for controlling the cold start valve.)

Try this: when your gauge is misbehaving and telling you your car is overheating, shut off the engine, then turn the ignition on without starting the car. What does the gauge indicate? If it suddenly behaves itself, you might have a bad engine ground.

Here's a thread wherein a bad engine ground is fixed.
DangerWillRbnsn
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Post by DangerWillRbnsn »

Thanks for the info and link Ron. Both part numbers I posted are temperature SENDING units. By year and model, I should have the two-prong.

In reality, I have a single-prong. Just wondering what's up.
LandCruzer94
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Post by LandCruzer94 »

I'm interested in this as well, after hitting Autozone I've realized that this isn't going to be that easy to find. I pulled the RealOEM diagram and took note of what we need, part #8, does this sound right? Mine also has a spade connector but with only one wire. Lets say if I do need a new sender, how would I retrofit the new one?

Image
DangerWillRbnsn
Posts: 442
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Post by DangerWillRbnsn »

LandCruzer94 wrote:I'm interested in this as well, after hitting Autozone I've realized that this isn't going to be that easy to find. I pulled the RealOEM diagram and took note of what we need, part #8, does this sound right? Mine also has a spade connector but with only one wire. Lets say if I do need a new sender, how would I retrofit the new one?

Image
Part number 8 is the part we are talking about. as you can see, even realoem shows a two-prong. visual inspection of the actual part on my car shows a single prong.

so my question remains (same as yours): what's the deal?
LandCruzer94
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Post by LandCruzer94 »

DangerWillRbnsn wrote:
LandCruzer94 wrote:I'm interested in this as well, after hitting Autozone I've realized that this isn't going to be that easy to find. I pulled the RealOEM diagram and took note of what we need, part #8, does this sound right? Mine also has a spade connector but with only one wire. Lets say if I do need a new sender, how would I retrofit the new one?

Image
Part number 8 is the part we are talking about. as you can see, even realoem shows a two-prong. visual inspection of the actual part on my car shows a single prong.

so my question remains (same as yours): what's the deal?
That's a single prong IMO shown in the diagram. I cross referenced the part on Autozone's website and came up with this: http://www.autozone.com/autozone/parts/ ... 2161360870
DangerWillRbnsn
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Post by DangerWillRbnsn »

LandCruzer94 wrote:
DangerWillRbnsn wrote:
LandCruzer94 wrote:I'm interested in this as well, after hitting Autozone I've realized that this isn't going to be that easy to find. I pulled the RealOEM diagram and took note of what we need, part #8, does this sound right? Mine also has a spade connector but with only one wire. Lets say if I do need a new sender, how would I retrofit the new one?

Image
Part number 8 is the part we are talking about. as you can see, even realoem shows a two-prong. visual inspection of the actual part on my car shows a single prong.

so my question remains (same as yours): what's the deal?
That's a single prong IMO shown in the diagram. I cross referenced the part on Autozone's website and came up with this: http://www.autozone.com/autozone/parts/ ... 2161360870
im on my phone right now so I can't see your link. but when I google the part number from #8 in realoem I see dual prong senders.
LandCruzer94
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Post by LandCruzer94 »

I think we're splitting hairs right now, but if you look REALLY closely at the realoem diagram I attached you'll see there's only one prong on the sender there, I'm just proving you're not crazy. Now I'm sure all the singles got replaced with the doubles at some point.
DangerWillRbnsn
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Post by DangerWillRbnsn »

LandCruzer94 wrote:I think we're splitting hairs right now, but if you look REALLY closely at the realoem diagram I attached you'll see there's only one prong on the sender there, I'm just proving you're not crazy. Now I'm sure all the singles got replaced with the doubles at some point.
thank you. I feel better knowing i am mostly sane. so if all the 'new' senders are dual-prong, how do I properly connect my single harness to the dual sender?
LandCruzer94
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Location: Simi Valley, California

Post by LandCruzer94 »

DangerWillRbnsn wrote:
LandCruzer94 wrote:I think we're splitting hairs right now, but if you look REALLY closely at the realoem diagram I attached you'll see there's only one prong on the sender there, I'm just proving you're not crazy. Now I'm sure all the singles got replaced with the doubles at some point.
thank you. I feel better knowing i am mostly sane. so if all the 'new' senders are dual-prong, how do I properly connect my single harness to the dual sender?
Well I think the second pole is to activate the overtemp warning light. All of these senders are advertised as "+ warning" which makes sense. I believe the unit still grounds through the body of the sender.
DangerWillRbnsn
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Post by DangerWillRbnsn »

so I can just plug my harness into either of the prongs on the new sender? or I need to seperate the two wires in my harness and put.one on each?
LandCruzer94
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Location: Simi Valley, California

Post by LandCruzer94 »

DangerWillRbnsn wrote:so I can just plug my harness into either of the prongs on the new sender? or I need to seperate the two wires in my harness and put.one on each?
That I don't know. If it works, it works I guess; just try it any way you can.
tn535i
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Post by tn535i »

If the two prong sender has one variable resistance terminal for the gauge and the other is a switch for OT. You need the variable side which is just like just like the single prong sender you already have. Sounds like you have no wires for the OT switch. If you don't trust it I would just replace it with the same thing.

Another possibility to consider is that this signal (very weak) just has a poor connection somewhere like the cluster or SI board or even the sender or where it atttaches to the Tstat housing.
demetk
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Post by demetk »

I haven't seen any e28's with the warning light on the gauge. My e23 has it though.
demetk
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Post by demetk »

DangerWillRbnsn wrote:so I can just plug my harness into either of the prongs on the new sender? or I need to seperate the two wires in my harness and put.one on each?
They're both the same wire color? So no you can't. One of them terminates at the diagnostic connector, the other to the gauge. The warning signal wire would need to be BR/GY if you had one.
Mike W.
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Post by Mike W. »

demetk wrote:I haven't seen any e28's with the warning light on the gauge. My e23 has it though.
E23s and E24s had the warning light in addition to the gauge. I never saw it light up on either, although on one E24 I had it was burned out. :shock: The larger prong, the 1/4" one, is the one for the gauge. The smaller one, 1/8" is for the light.
DangerWillRbnsn
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Post by DangerWillRbnsn »

Image

this is my current setup. both wires are Brn/wht. so just plugs.into the bigger connector on my new sender? [/img]
demetk
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Post by demetk »

DangerWillRbnsn wrote:this is my current setup. both wires are Brn/wht. so just plugs.into the bigger connector on my new sender?
On the e23 the warning light is connected to the small terminal and the temp gauge is connected to the large terminal via the brown/white wires.
DangerWillRbnsn
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Post by DangerWillRbnsn »

Thank you. I put the new one in today and just plugged into the larger of the two prongs, leaving the small one with nothing. temp gauge seems to be working now. It is no longer twitchy. however, now I never seem to fully warm up. it just.hovers at slightly.more than 1/4 after idling for 10 minutes. I don't know if that's accurate or not but whatever, at least I know its not overheating.
TSMacNeil
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Post by TSMacNeil »

1/4 scale is just right. Sounds like it's fixed.
DangerWillRbnsn
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Post by DangerWillRbnsn »

TSMacNeil wrote:1/4 scale is just right. Sounds like it's fixed.


sweet! does anyone have a rough approximation of temperature at the indications on our gauges? 1/4 temp = 190* maybe? I am not currently running a thermostat. I have one on the way, but fir now nothing.

wondering at what point I should start to worry is all.
TSMacNeil
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Location: Phoenix, Arizona

Post by TSMacNeil »

Yes, Rod Paine collaborated with ShawnD...it's here somewhere, but I'll look at Rod's site for you...stand by
http://www.mye28.com/tech/rods_pages/
it's in his "maintenance tips page 2"...but bookmark his site.
It will be obvious why...
;)
tn535i
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Location: Middle Tennessee

Post by tn535i »

On my e30's, e28 and e24 they all run about midway when fully warm unless the t-stat is stuck open. Did you just say you don't have a t-stat in there? Expect it to run cold, surprised it's not staying in the blue now but probably not overheating for sure.

I'm guessing midway is about 180F where the std t-stat will open.
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