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2004 Crossfire no cranking but fan running
Car doesn't crank but fan runs really fast once I turn key all the way. Battery is fine. Coolant and oil is good.
I waited for car engine to get cool and it cranked right up. This happens very often. I read other threads that it can be the K40 module or relay fuse. Where can I find the k40 module? Can someone please let me know how to fix this? |
Re: 2004 Crossfire no cranking but fan running
Originally Posted by REYMARTZ
(Post 873444)
Car doesn't crank but fan runs really fast once I turn key all the way. Battery is fine. Coolant and oil is good.
I waited for car engine to get cool and it cranked right up. This happens very often. I read other threads that it can be the K40 module or relay fuse. Where can I find the k40 module? Can someone please let me know how to fix this? The fast fan may be the fan control module failing. Fix the RCM first though. Add more details of what went wrong first, full info makes it easier to solve or at least get relevant ideas as to the problem. |
Re: 2004 Crossfire no cranking but fan running
It's the Engine Control Relay in the RCM.
Email me tighed1@hotmail.com and for $27 I'll replace the relay along with the air pump relay. Solder bad joints and give ya the Me So Horny mod (horn works without the key). |
Re: 2004 Crossfire no cranking but fan running
Yup, you are powering up the Fan Module but not the ECM, so the Fan Module is going into Emergency Mode as it was designed too.
Fix yer RCM or send it to DJ (Post 3) and he will fix it for you. |
Re: 2004 Crossfire no cranking but fan running
Originally Posted by pizzaguy
(Post 873471)
Yup, you are powering up the Fan Module but not the ECM, so the Fan Module is going into Emergency Mode as it was designed too.
Fix yer RCM or send it to DJ (Post 3) and he will fix it for you. |
Re: 2004 Crossfire no cranking but fan running
Dave, first sentence, post 1.
As soon as you turn the key on, the FCM is powered up. If it does not see the "are you there?" pulses from the ECM, it goes into emergency mode and runs at 100% speed. IF the output from the engine control relay is not there to power up the ECM, the ECM does not send "are you there?" pulses to the FCM and it does not send the enable to the pulse module to engage the starter. Resoldering the RCM or changing the relay on the RCM (depending on if the relay is bad or the solder connections are bad) fixes all of this. Also: There is a constant handshaking going on between the FCM and ECM. If the FCM does not see the pulses from the ECM, it goes into emergency mode. If the ECM does not get it's handshakes from the FCM, it lights the "low coolant" light. |
Re: 2004 Crossfire no cranking but fan running
Just an additional note on this "fan runs full speed" thing :
If the IAT sensor is faulty or unplugged on an NA, the engine will start and run, but the fan will crank up to top speed also. You will also get a CEL - don't remember the P code, I just cleared it out. Ask me how I know this ;) |
Re: 2004 Crossfire no cranking but fan running
And is it true that the IAT sensor is integrated in the MAF sensor?
|
Re: 2004 Crossfire no cranking but fan running
Originally Posted by pizzaguy
(Post 873490)
Dave, first sentence, post 1.
Have the cause been taken from the Mercedes forum or what? |
Re: 2004 Crossfire no cranking but fan running
Well, I got my explanation from grabbing an oscilloscope and probing that line from the ECM to the FCM and figuring out that they were using a pulse width modulation technique to tell the FCM what speed to run the fan. (The FCM also uses PWM to vary the fan speed - but that's not the point here.) (This after Rudy told me part of it, back in 2009 - I then started my own investigation cause I can't NOT know!)
I could see the pulses going back and forth during times when the ECM was not telling the fan to run at all - you could easily see the handshake. |
Re: 2004 Crossfire no cranking but fan running
Hit the button too soon...
Anyway, it was obvious to me what was going on, I'd cut the wire and the fan took off and the light came on. It was only a matter of measuring the width of the pulses to figure out what they were doing. I could see the pulses from the ECM get wider when I turned the A/C on, then even wider as the temp needle went past 1/2 way. I then used a function generator to simulate the ECM to make the FCM do what I wanted - THAT was a challenge. But then the performance shop in ATL charged me only $50 to reprogram the ECM for a lower fan-on temperature. I then stopped by research into how to have a "dial it up on the dash" fan speed. |
Re: 2004 Crossfire no cranking but fan running
Originally Posted by pizzaguy
(Post 873500)
And is it true that the IAT sensor is integrated in the MAF sensor?
|
Re: 2004 Crossfire no cranking but fan running
Originally Posted by pizzaguy
(Post 873510)
Hit the button too soon...
Anyway, it was obvious to me what was going on, I'd cut the wire and the fan took off and the light came on. It was only a matter of measuring the width of the pulses to figure out what they were doing. I could see the pulses from the ECM get wider when I turned the A/C on, then even wider as the temp needle went past 1/2 way. I then used a function generator to simulate the ECM to make the FCM do what I wanted - THAT was a challenge. But then the performance shop in ATL charged me only $50 to reprogram the ECM for a lower fan-on temperature. I then stopped by research into how to have a "dial it up on the dash" fan speed. What I have intended to do for a long time is to start a thread where all the known problems and their solutions are listed, then they can be put in the Crossfire problem index. They would all be combined in a .pdf format, whoever writes the post will get full credit of course. Just a simple list of symptom(s), and repair, nothing fancy just keeping to the straight facts. Just gimme the facts as Joe Friday would say. We have all these answers spread all over the forum and some are hard to find and the questions are asked over and over again. Does that sound feasible? You can copy someone else's post, just give due credit so that both can be credited. |
Re: 2004 Crossfire no cranking but fan running
Ever see one of those old Heathkit troubleshooting charts ?
It is a kinda reverse bubble flow chart that starts with "I have a problem", then leads down through different boxes with various paths leading out of them as defined by the description choices in the boxes like "engine", "body", "brakes" etc. Maybe that would be an idea ? Or not. |
Re: 2004 Crossfire no cranking but fan running
Originally Posted by onehundred80
(Post 873513)
What I have intended to do for a long time.........Does that sound feasible?
Originally Posted by ala_xfire
(Post 873515)
Ever see one of those old Heathkit troubleshooting charts ?
It is a kinda reverse bubble flow chart that starts with "I have a problem", then leads down through different boxes with various paths leading out of them as defined by the description choices in the boxes like "engine", "body", "brakes" etc. Maybe that would be an idea ? Or not. |
Re: 2004 Crossfire no cranking but fan running
Originally Posted by onehundred80
(Post 873506)
I wanted to know where the cause of the symptoms appeared on the forum before.
Have the cause been taken from the Mercedes forum or what? First time I think I actually mentioned it was here. https://www.crossfireforum.org/forum...tml#post866312 |
Re: 2004 Crossfire no cranking but fan running
Originally Posted by tighed1
(Post 873559)
In the past I was encountering RCMs that didn't start and the fan would spin up. Never took the time to figure it out (sent RCM back to owner with an apology). It bugged me for quite sometime so one day I decided to find out why it was happening. Been fixing that issue ever since.
First time I think I actually mentioned it was here. https://www.crossfireforum.org/forum...tml#post866312 CLICK Took me ten minutes to find the solution when I had the symptoms. |
Re: 2004 Crossfire no cranking but fan running
Originally Posted by onehundred80
(Post 873571)
Took me ten minutes to find the solution when I had the symptoms.
Sounds like yer accusing me of claiming credit for a solution, again. Both times you pointed this out my work was my own. Wouldn't have spent the time and effort figuring things out had I known the solution was already out there. I suppose there is lot to learn on some of the MB sites as our car are similar. If it makes ya feel better Dave, here's this: "I tighed1 hereby give all credit for the Mystery No Start and fan running at high speed (no start) solutions to the good folks that discovered them on other forums, prior to my discovery of the same issues." Feel better now? :rolleyes: I suppose that since I actually have a "real" Mercedes now I should frequent those MB sites too lol! |
Re: 2004 Crossfire no cranking but fan running
Originally Posted by tighed1
(Post 873577)
And you didn't tell us about the solution because??
Sounds like yer accusing me of claiming credit for a solution, again. Both times you pointed this out my work was my own. Wouldn't have spent the time and effort figuring things out had I known the solution was already out there. I suppose there is lot to learn on some of the MB sites as our car are similar. If it makes ya feel better Dave, here's this: "I tighed1 hereby give all credit for the Mystery No Start and fan running at high speed (no start) solutions to the good folks that discovered them on other forums, prior to my discovery of the same issues." Feel better now? :rolleyes: I suppose that since I actually have a "real" Mercedes now I should frequent those MB sites too lol! If you read this thread you will find that I only learned the symptoms on the 2nd of this month. I did the search of the SLK forum today and I soon learned, in 10 minutes, that the cause was what you and PizzaGuy said they were. In both cases I have said that the solution had been discovered years ago on the Mercedes forums and they all come to light in a single thread started by Bazzle from Oz on the RCM solder issue and another guy on page three of the high speed fan/no start issue. You took offense at the RCM post, at that time you said they should have told us years before you/we found out.:rolleyes: |
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