Strange cooling issues
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Joined: Sep 2007
Posts: 70
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From: North West PA
Strange cooling issues
Alright, let me run this past you guys:
Last month or so, I've been noticing my cooling fan comes on at some odd times. Sometimes 120 degrees, other times 151 degrees. Seems to be completely random, never same temp twice. I haven't been driving it much, so didn't really pay much attention to it. Fast forward to last week, I noticed it wasn't just the primary fan coming on, but both fans, at the same time. My engine began to stall out when the fans came on, and on friday once the fans came on (at 119 degrees) the engine failed all together and wouldn't restart. Once the car cooled down, started fine and drove untill the fans came back on, then sputtered and died again. While this was happening, a couple of my gauges, tack and oil pressure, spiked all over the place.
Sooooooo.....
my thoughts are, after checking out the temperature sensors and relays to ensure they were in proper working condition, and cleaning all of my grounds, that I must be experiencing an ECM problem. Correct me if I'm wrong, but the ECM reads the temperature from the sensor in the cylinder head on passenger side, then closes the ground on one or both of the fan relays to make them work. So, my logic says that if it's happening at a random time, and all of those parts are working correctly, it can only be the ECM.
The other issue of it refusing to run could be stemming from that as well, though I figured if I could pin the cooling fan problem down, the stalling would either be fixed as well, or I could work on it next.
I'm about to order a new (rebuilt) ecm, but wanted some opinions, thanks in advance guys.
Also, I've found ecm's at mid america...any other places you guys know of that don't require me to send in the ecm to be rebuilt, just want it back as a core?
Zane
Last month or so, I've been noticing my cooling fan comes on at some odd times. Sometimes 120 degrees, other times 151 degrees. Seems to be completely random, never same temp twice. I haven't been driving it much, so didn't really pay much attention to it. Fast forward to last week, I noticed it wasn't just the primary fan coming on, but both fans, at the same time. My engine began to stall out when the fans came on, and on friday once the fans came on (at 119 degrees) the engine failed all together and wouldn't restart. Once the car cooled down, started fine and drove untill the fans came back on, then sputtered and died again. While this was happening, a couple of my gauges, tack and oil pressure, spiked all over the place.
Sooooooo.....
my thoughts are, after checking out the temperature sensors and relays to ensure they were in proper working condition, and cleaning all of my grounds, that I must be experiencing an ECM problem. Correct me if I'm wrong, but the ECM reads the temperature from the sensor in the cylinder head on passenger side, then closes the ground on one or both of the fan relays to make them work. So, my logic says that if it's happening at a random time, and all of those parts are working correctly, it can only be the ECM.
The other issue of it refusing to run could be stemming from that as well, though I figured if I could pin the cooling fan problem down, the stalling would either be fixed as well, or I could work on it next.
I'm about to order a new (rebuilt) ecm, but wanted some opinions, thanks in advance guys.
Also, I've found ecm's at mid america...any other places you guys know of that don't require me to send in the ecm to be rebuilt, just want it back as a core?
Zane
Melting Slicks
Joined: Feb 2010
Posts: 2,077
Likes: 72
From: Reno Nv
Have you pulled the codes?
BTW, finding a 1992 ECM somewhere will be like winning the lottery. The 92 is unique. I've searched a couple of times cause I wanted a spare, no luck
Mid Am will just send your's to a rebuilder.
Someone here mentioned these guys www.siaelec.com , decent web site, no 92s of course, you'd have to call them.
BTW, finding a 1992 ECM somewhere will be like winning the lottery. The 92 is unique. I've searched a couple of times cause I wanted a spare, no luck
Mid Am will just send your's to a rebuilder.
Someone here mentioned these guys www.siaelec.com , decent web site, no 92s of course, you'd have to call them.
Last edited by Bill32; Mar 26, 2010 at 10:42 AM.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Signal is from the Coolant Temp Sensor and on the LT Motors, I thought that was screwed into the WP. You should scan it or just buy another Sensor and plug it into the harness (make sure the harness is good too). Sensor is used for fuel delivery (along with non a/c fan control) so if it's sending the wrong info, it's either going to get too much or too little gas and run like crap - or not run like you're seeing. You might also verify the 5 volt reference - yellow wire. With the harness Disconnected or the yellow wire grounded, it should spit out a 15/14 which will at least show that the ECM diagnostics are working.
