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I have an S2 2009 6 speed auto with the flappy paddles,
owned it since new mainly as a weekend car when I get to do a lot of fast hilly corners. In the first flush of ownership used as a daily driver. It's very hot here, always, no let up, 24-38C (night lowest and day highest), incredibly humid and it rains a lot. In 12 years ownership I've just done 24,000km! Coolant bottle replaced 3 years ago after sensor float failure. New spark plugs around 23000km and just regular oil changes (mineral10w-30) @ 6 month intervals and other fluid changes as shown in the service book. The local dealer not experienced at all in rotary engines, so had to learn myself about my baby. After a recent thrashing, backing into my drive, steam and coolant started pouring out from the coolant bottle. Sigh.......
Possibly the water pump, thermostat or the cooling fans. It's one of those things. Not great to overheat this engine as it can easily be ruined or damaged. Definitely need to find the culprit.
Checked the fans with direct connection from the battery, they both work fine, and at high speed. Ran the engine up to temperature and the top and bottom radiator hoses were hot so I assumed water pump working, as there were no leaks around the housing either. Coolant temp @ 90C and still the fans didn't come on. Checked all the relays by plugging into horn relay slot, all 3 working fine. Still the fans refusing! Haven't checked the temp sensor yer, still trying to get to it.
I read somewhere the S2 PCM controls the fans and through the relays switches the power. With all our lockdowns I disconnected the battery several times and my baby sat idle for about 3 months several times. Could the PCM be the culprit?
It's not the PCM. Is 90 as high as the temperature got? Meaning the car was able to maintain 90c without turning on the fans? That's not really unusual, if it got higher and still no fans, I would start to be concerned.
Do they come on when if you warm up the car, turn it off, and turn it on again? Do they (or 1) come on with the A/C turned on?
When you say the fans turn with direct battery voltage, do they both turn?
Steam a e coolant coming out of the overflow could be the overflow cap not securely installed or the overflow tank is cracked. They love to crack around the cap.
Welcome to the forum!! You have a beautiful S2. If you are questioning coolant seal failure, I would recommend pressurizing the cooling system with a cooling system pressure tester and seeing if the system has pressure. If it does not and no external leaks are present, you will know then that you have a bad coolant seal. Here's hoping you do not as the car appears to have been well cared for and the mileage is very low.
Thanks!
I hope its not a coolant seal failure. I'm not losing any coolant and the engine has been run a lot (car static) since the first overheating. The temp went up to 105C at one point before I turned it off, still no fans running. Dare not risk driving it as it will boil over again in traffic jams. The idle is quite stable around 870 with no apparent misfires, starts ok hot or cold, no issue. No CEL, and the OBD not showing any fault codes. I'm reading the temps from the OBD. Before this issue happened, the fans would come on after I shut down the engine following a hot run, and stay on for up to ten minutes to cool the engine bay, ...now that does not happen.
I can't help feeling this is some kind of sensor issue.
It's not the PCM. Is 90 as high as the temperature got? Meaning the car was able to maintain 90c without turning on the fans? That's not really unusual, if it got higher and still no fans, I would start to be concerned.
Do they come on when if you warm up the car, turn it off, and turn it on again? Do they (or 1) come on with the A/C turned on?
When you say the fans turn with direct battery voltage, do they both turn?
Steam a e coolant coming out of the overflow could be the overflow cap not securely installed or the overflow tank is cracked. They love to crack around the cap.
The temp went up to 105C then I chickened out and turned it off, no cooling fans came on (went off at that temp). I did check both fans with a direct battery connection and both fired up. The coolant fan (left) comes on slowly around 86C .........with the a/c on I cannot see because battery and air box in the way, I think I can hear them but very quiet, like they cannot run at high speed, Then when the temp gets to 90+ or so, both fans turn off! I think the relays Fan2 and Fan 3 are for higher speed running controlled by the PCM/ECU, checked all the relays and the seen ok. The coolant tank was replaced with Mazda's upgraded version where they supposed to fix the float problem, so it looks intact still and the rad cap is fine. I just go myself a pressure tester so will try to pressurize the system but I feel the fan controller is the issue here.
Last edited by Becky245; 04-12-2021 at 02:50 AM.
Reason: spelling
I see. You're right, the fans are supposed to turn on high speed instead of off. They do wear out with time so it's possible they've had it, especially if slow speed is too slow. But I have a feeling it's not that easy. Not 100% on how the high speed circuit is made, but would start there. The shop manual at foxed.ca may help.
I see. You're right, the fans are supposed to turn on high speed instead of off. They do wear out with time so it's possible they've had it, especially if slow speed is too slow. But I have a feeling it's not that easy. Not 100% on how the high speed circuit is made, but would start there. The shop manual at foxed.ca may help.
I think I found it.
Thank you so much for the manual link at foxed ca....I used the manual link fro Ash previously but couldn't find any reference to these codes. I need to upgrade my Foxwell OBD scanner with their latest Mazda software...hopefully will find the fault codes!
It gets worse...the engine cranking over but cannot start. When I turn the ignition on, the starter relay clicks rapidly, (the relay in the fuse box, not the starter solenoid), the engine cranks over but cannot start. Replaced the relay, new battery....still the same.
Yeah it's the starter relay rapid clicking in the fusebox, as soon as I turn on the ignition without even starting it's hammering away. I can crank the engine, but it will not start. If I pull the relay, of course the clicking stops. I think I messed up the PCM. I was testing the relays for the cooling fans, earthing the #Fan 1 and #Fan 2 relays to the negative side of the battery. Fan#1 didn't come on, Fan#2, the right fan came on turning slowly so I know Fan#1 motor is dead. Then I tried the same with Fan#3 relay, ignition on, earth to neg terminal and big spark then the rapid clicking of the starter which didn't go off until the ignition turned off.
Fan#3 relay is controlled by the PCM signal, It turns on the fans when the car has stopped and it detects a high engine bay temperature, so it turns the fans on full to cool itself, the PCM. I think I fed a high current to the PCM! It's fucked, ......I know it is!. Sigh.........
And then my cat died last Tuesday. Bad things happen in 3's, I'm expecting a big repair bill!
Last edited by Becky245; 04-25-2021 at 01:45 PM.
Reason: correction
Yeah it's the starter relay rapid clicking in the fusebox, as soon as I turn on the ignition without even starting it's hammering away. I can crank the engine, but it will not start. If I pull the relay, of course the clicking stops. I think I messed up the PCM. I was testing the relays for the cooling fans, earthing the #Fan 1 and #Fan 2 relays to the negative side of the battery. Fan#1 didn't come on, Fan#2, the right fan came on turning slowly so I know Fan#1 motor is dead. Then I tried the same with Fan#3 relay, ignition on, earth to neg terminal and big spark then the rapid clicking of the starter which didn't go off until the ignition turned off.
Fan#3 relay is controlled by the PCM signal, It turns on the fans when the car has stopped and it detects a high engine bay temperature, so it turns the fans on full to cool itself, the PCM. I think I fed a high current to the PCM! It's fucked, ......I know it is!. Sigh.........
And then my cat died last Tuesday. Bad things happen in 3's, I'm expecting a big repair bill!
Can you make a video of what you're talking about?
Let's not jump to conclusions, there are many diagnostic steps before concluding the problem is the most expensive one, the PCM. The point of a relay is not to send current through the sensitive computer stuff and instead have a "small" signal switch a bigger current. So depending on which pin you earthed, all you might have done is short battery+ to -, which explains the big spark and such. Also everything is protected by fuses, so PCM failure would be far down my list of potential culprits.
- are any fuses blown?
- what's the battery voltage?
- have you confirmed it's not flooded?
- what rpm is it cranking at? (you need an OBD reader to get the actual number)
- any OBD codes?
Also the starter relay is unpowered in any key position except "START", another reason it doesn't super make sense for the starter relay to be clicking with the key in ON. The headlight relay is right next to it, are you sure we're talking about the ST relay?
OK so....
-no fuses blown
-new battery reading 13.9V on my multimeter
-it's not flooded. taken out the plugs, they are dry (may have flooded the first time this happened)
-it cranks at 250 no problem
-OBD says no codes present. I tried 3 different readers, including Foxwell with Mazda specific software.
The starter relay starts its rapid clicking when the key is in the "on" position (3rd indent), I can hear the starter solenoid clicking in unison, so yes, it doesn't make any sense!
It's not the HD relay, I broke that one trying to pull it out! Was going to swap it over with the ST, they are the same.
My thinking is maybe the ground has melted to the starter circuit? Before this happened, when I turn the key to the "on" position, the starter relay and starter solenoid click into place so that turning the key to "START" will crank the engine and it fires up. So there must be power going to the starter relay in the "on" position, so the starter solenoid can engage? But now when I do this, the engine will crank but the starter relay and starter solenoid just keep on rapid clicking! And the engine don't start! So the PCM can't fire up the engine. I disconnected the fuel pump relay, to try and resolve the clicking, so the engine won't flood, (hopefully).
I will do a video of the rapid clicking later, had to go to the office this morning for boring work, but I'm scared about trying to start the engine because the starter motor bendix may expire with the solenoid keep on clicking! I need to figure out why the rapid clicking. The other puzzle is why did this happen when I was messing with Fan#3 relay? The only connection I can see is that the PCM sends a signal to this relay when the engine compartment gets too hot and the car is stationary, so maybe I send a 60amp shock into the PCM when I earthed the #3 fan relay terminal
The thing you're touching is the ignition relay, not the starter. So that part makes a bit more sense.
If you swapped those two around, and the clicking traveled with the relay, then for whatever reason the relay itself is unhappy. It won't start without both of those relays in good shape, but the good news is if the clicking travels with the relay, it's just the relay.
I can't quite see the gauges when you try to start it, but if you're getting data via the OBD and the gauges move, the ECU should be mostly working.
Yes it's the relay in the ignition position on the fuse box that's doing all the clicking. I swapped all these type of relays around,,HD, ST and IGNITION into the ignition position relay slot and they all clicked, so the clicking did not travel with the relay, so I assumed it is coming from a signal in the terminal in the socket. So I did a bench test of all the 3 relays for switching and continuity and they all passed fine, (then I broke the casing on one). These are really expensive items, around US$39 each excluding shipping, so if they work on the bench then an necessary expense to replace if the fault is in the wiring or the ECU.
I checked the wiring diagram and there is a ground signal wire from the PCM to the fan relay #3 terminal, the one i earthed to the battery when testing the fan motors, and it's when the clicking of the ignition relay started. It's a ground that goes into the PCM. I'm still looking for the connection between the two on the wiring diagram, hope it's not a messed up PCM, but I have a ECU repair specialist looking at the PCM in the next few days just to check all in order. I can't think of what else to check, so it looks like I'm going to be in the replacement of components until problem solved? That's what the local dealership suggested!
OK. That's good info. A relay will click like that if there's too much resistance in either the ground or power side of the control signal. Looking at the wiring diagram, the ignition relay doesn't go through the ECU anywhere. It gets turned on via the ignition switch and grounds immediately. So if that position is clicking, I would check the ground it's connected to. You may need to unbolt the fuse box to better trace that. It's possible it shares a grounding point with the relay you shorted.
Actually it looks the Ignition relay and the cooling fan relay you shorted don't share a ground, the cooling fan relay grounds through the ECU. Still, the whole circuit is on a 15A fuse, I would expect it to blow before damage was done.
So wait you connected the cooling fan relay's control ground to battery negative? That's ground to ground, it shouldn't have done much. Exactly which pins did you connect where?
The cooling fan test started with Fan##1 relay, i connected a wire to the ground terminal on the relay, like this
Then I plugged it back into the fusebox, turned ignition key to "on" position and touched the other end of the wire to the -ve battery terminal. The cooling fan #1 did not come on. I repeated this with cooling Fan#2 using the same relay and #1 relay in place and the cooling fan #2 (A/C on) came on working at normal speed, seemed quite fast. Then I repeated the same process on Fan#3 and boom that's when my problems started, immediately the clicking began on the ignition relay
There is a signal wire coming from the PCM to Fan#3 relay. I don't see though how this is connected to the ignition circuit. It should be from Mazda's description on how the PCM turns on the cooling fans after the ignition is turned off and the engine compartment temperature is too high. They did this to protect the components in the engine bay from high temperatures .(they say) after a hot run with the engine off. It's a "normal" service on my other cars, the electric fans come on even after the engine is shut down when the temperature is very high
Well that's the thing. The fan circuit isn't connected to the ignition relay at all. Have a look at wiring diagrams if you haven't already. The Ignition relay and circuit ironically has very little to do with the actual ignition and more to do with all the components that turn on when you put the key to ON: wipers, defrosters, steering and ABS control, etc. Can you check if the wipers work at all? Weird one, I know, but I'm curious if the get ant current at all, but intermittently in time with the clicking, or not at all. The clicking is a bit slow to be your usual relay problem.
So whatever your grounding adventure damaged, it would have to be something both the cooling fan circuit and the ignition circuit have in common... which appears to be .. ground?
Just to be clear, what you're calling the ground of the relay, which you connected in the shown fashion, is the control ground? Not the switched load output?
Well that's the thing. The fan circuit isn't connected to the ignition relay at all. Have a look at wiring diagrams if you haven't already. The Ignition relay and circuit ironically has very little to do with the actual ignition and more to do with all the components that turn on when you put the key to ON: wipers, defrosters, steering and ABS control, etc. Can you check if the wipers work at all? Weird one, I know, but I'm curious if the get ant current at all, but intermittently in time with the clicking, or not at all. The clicking is a bit slow to be your usual relay problem.
So whatever your grounding adventure damaged, it would have to be something both the cooling fan circuit and the ignition circuit have in common... which appears to be .. ground?
Just to be clear, what you're calling the ground of the relay, which you connected in the shown fashion, is the control ground? Not the switched load output?
Yes it was the control ground. I have tested all the ground connections, and the control grounds are good. I'm not getting any readings from the OBD, the PCM seems totally unable to communicate, .U0073 code.
Also no gauges working, no rpm on cranking....nothing. Looks like the PCM has expired. Relay still happily clicking away.
So the PCM has expired, apparently a 12v power was applied (by me) to the ground signal wire from the PCM to Fan# 2 relay and as we know these computers don't like reverse polarity currents. It's in for analysis and repair, if possible. If the memory chips were undamaged, maybe it will not need a reflash, as the dealer here stopped doing these years ago. These cars were an oddball for them, the arrangement with Mazda for the franchisee was to take them and sell as part of the deal, so they never really bothered. Maybe someone knows who can, even by mail?
PCM still at the electronics shop, looking for issues. No fault codes were recorded on the unit. Now I'm looking for rodent damage. Car still idle, up on jack stands!
04-10-2021, 04:30 AM
Newbie here
