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So, yesterday I replaced the coolant temp sender in my 86. The sender threaded into head between the 6 and 8 spark plugs. I plugged the wire into the sender, which was the same one that came off of the sender. Green coated single wire with a female spade connector. Engine was running and then the sender exploded into a ball of fire and blew the center out.
I did some digging and it appears that the green wire I hooked up to the sender also runs to the starter. This tells me that there was power going to that sender. I don't know if I messed something up or if the previous owner had something routed improperly. I'm going to remove the starter today and check and clean the oil and coolant off of the wiring and get a better look at what's going on. Here is a picture of the wire in question:
That's the correct wire. It should be bolted to the block to keep it away from the exhaust.
It runs in the same wire loom with the purple wire which runs to the starter solenoid. I would test the green button pigtail for voltage before you do anything else.
Why did you replace the sensor? Did the other one explode too? Sounds interesting.
I replaced the sensor because my coolant temp gauge reads "LO" and won't budge. I figured I'd start there and install a known good sensor. The original sensor did not explode. It was there hooked up to that wire as it should be.
I see the bracket dangling off of the green wire. Seems like it should be bolted to the block as it did on my 84. Maybe I'll see if I can find where it shoulddbe bolted and attach it to the block again.
I replaced the sensor because my coolant temp gauge reads "LO" and won't budge. I figured I'd start there and install a known good sensor. The original sensor did not explode. It was there hooked up to that wire as it should be.
I see the bracket dangling off of the green wire. Seems like it should be bolted to the block as it did on my 84. Maybe I'll see if I can find where it shoulddbe bolted and attach it to the block again.
This is from an '87 FSM and it's what I'd think you'll find.
There should be another longer wire for the knock sensor coming from that loom I just replaced my knock connector and it was a single connector also. I remember if it was green.
I always thought the guauge sensor is between 1-3 cyl on the drivers side.
The knock sensor is on the bottom of the block on the passenger side on this car. Perhaps this is an early 86 with the temp sender in the old location.
Its just odd to me as to why that temp sender wire has 12V running thorugh it
There should be another longer wire for the knock sensor coming from that loom I just replaced my knock connector and it was a single connector also. I remember if it was green.
I always thought the guauge sensor is between 13 cyl on the drivers side.
I'd expect DK BLUE for knock from the ESC module but routed around and "in the vicinity".
I'm quite sure the FSM uses the left cylinder head for the location BUT maybe that's the location for an 86E with perimeter covers and NON aluminum heads. FSM maybe went to publication before the head change was confirmed? Maybe very likely.
I have the aluminum heads and the bolts that hold the valve covers on are in the center not around the perimeter like they are on the iron head
I would check this sensor
This was an 87 engine I believe. Then sort that other side out and put a new sensor for your aux fan. You should have a little fan in front of the radiator. Or put the old sensor back since it is not for the guage.
There's no sensor there on my 86. I'll post a picture..
I have an 86 in the UK my temp sensor is between 6/8. The knock sensor is at the bottom of the block just behind the starter motor.
the temp sensor will not have 12v... it will have 5v maximum. If you have the correct wire fitted you must have a short somewhere...could be sending 12v to the pcm on a 5v wire....not good.
Sid hey ther that sensor is the knock sensor, do you have any sensors between 1-3 cyl on the drivers side where I circled in the pic?
No I've got nothing there, only between 6/8.
both sensors ( temp n knock ) are single wires going into conduit above the starter motor. I do remember another single wire comeing from the starter solonoid which I thought at the time was strange but I don't know where it went. Again it went into the conduit and disappears.thinking about it.. it could have been the fuseable link wire, not sure
So what we are saying is 1986 (probably late) does not have the sensor between 1-3 as the 85 and 87 do. That means the guage in the dash is pulling its reading from the sensor between 6-8 or from the engine coolant sensor on the front of the manifold. If no auxiliary fan I guess the sensor between 6-8 would make sense to get the dash temp.
I have a late 86 with aluminum heads. In pic 2 there is no sensor/sender between 1 and 3 on the drivers side. There is a sensor/sender between 6 and 8 in pic 3.
Now it appears that this thread only needs an '86e owner before aluminum heads to confirm how his is assembled. I looked as the '86 FSM again this evening and I saw another error I believe. The wire to the sender in the cluster wiring diagram seems to go from GREEN @ cluster to BLUE at the sender. We all know that's incorrect!!
I can confirm without a doubt that the coolant temp sender for the gauge is in between the number 6 and 8 spark plug on my 86. There is nothing between the 1 and 3 spark plugs. The build date on my 86 is 4/86. I didn't have a chance yesterday to get much done other than replace the spark plugs. The new AC Delco wires came in yesterday and the new temp sender comes in today.
I need to get the car in the air and check that green sender wire for high voltage. I had considered the ECU feeding it more than 5V. I think if I'm able, I'll solder in a new wire section specifically for the temp sender as the wiring is pretty shabby. I'm also concerned that the sender wire being as loose as it was, grounded itself to the power terminal on the starter. If I follow the wire down, it seems as though its attached to the starter. But, it was full of oil and coolant so I need to remove the starter and get everything clean and then have a better look at what's going on down there.
I can confirm without a doubt that the coolant temp sender for the gauge is in between the number 6 and 8 spark plug on my 86. There is nothing between the 1 and 3 spark plugs. The build date on my 86 is 4/86. I didn't have a chance yesterday to get much done other than replace the spark plugs. The new AC Delco wires came in yesterday and the new temp sender comes in today.
I need to get the car in the air and check that green sender wire for high voltage. I had considered the ECU feeding it more than 5V. I think if I'm able, I'll solder in a new wire section specifically for the temp sender as the wiring is pretty shabby. I'm also concerned that the sender wire being as loose as it was, grounded itself to the power terminal on the starter. If I follow the wire down, it seems as though its attached to the starter. But, it was full of oil and coolant so I need to remove the starter and get everything clean and then have a better look at what's going on down there.
In your snapshot of the wire the actual connector is missing, only the terminal is shown. Do you have the connector and just removed the terminal for a visual OR you don't have? What part # did you order for the sender this time? I believe I can provide the connector information. There's 2 types, a spade(most common) or a "button" (less often) but the same connector won't work for both. The terminal will.
This GM # 6288704 should be available likely on most dealers shelves. It will work for the spade & "button". GM # 2977253 for just the spade is maybe today a harder find. If you shop local and just ask for Packard 56 series connector shell you might actually do well. Amazon or eBay for images and a last resort for a purchase.
04-25-2017, 06:40 AM
Coolant temp sender....exploded
