To save typing a long reply I would point you to this. It gives the location and very helpful advice on replacing the sensor. Note especially the section on not prising the sensor out of its hole.
I have never heard of programming it to the computer. You will have to erase the code or the engine will assume that the sensor is still faulty.
Bill.
Timing belt Volvo 740 200k miles.
This topic is in the MVS Volvo Repair Database »
Timing Belt Replacement Tips Volvo 740
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billofdurham
- MVS Moderator
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Re: Timing belt Volvo 740 200k miles.
Work was good - retirement is better.
1996 850GLT 2.5 20v Estate Manual.
1995 Peugeot Boxer 2.5Tdi Autosleeper.
Previously:
1984 244DL, Manual, Beige.
1987 744GLE, Manual, Green.
1991 960 3.0 24v, Auto, Silver.
1994 940T Wentworth, Auto, Blue.
1996 850GLT 2.5 20v Estate Manual.
1995 Peugeot Boxer 2.5Tdi Autosleeper.
Previously:
1984 244DL, Manual, Beige.
1987 744GLE, Manual, Green.
1991 960 3.0 24v, Auto, Silver.
1994 940T Wentworth, Auto, Blue.
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Retired MVS Contributor
It is also known as the impulse sensor...It is located at the back of the engine on the left side just below and next to the distributor...It is mounted on a bracket that is attached to the back of the engine block...One 10mm screw pointing downward holds the sensor in the bracket...The sensing unit points through a small hole in the flywheel housing...It counts PRM and sets ignition timing by counting drilled holes in the flywheel...The engine will not start if it is not working...
As far as I know, there is no programming requirement although I have never had to replace one...
Jerry
As far as I know, there is no programming requirement although I have never had to replace one...
Jerry
OK here is the latest,
I replaced the 'crankshaft position sensor' and reset the OBD diode. Vehicle does not start still. Should I take a hammer to this vehicle? Any last minute suggestions are most appreciated. Thanks.
I replaced the 'crankshaft position sensor' and reset the OBD diode. Vehicle does not start still. Should I take a hammer to this vehicle? Any last minute suggestions are most appreciated. Thanks.
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Retired MVS Contributor
Not yet!... 
I would re-check the belt timing...The diagram supplied by Kmaniac is where it should be...You will need to remove the upper belt cover to check it and you should be able to see the lower mark with a strong flashlight without removing the crank pulley and lower cover...Line up the camshaft mark at the top and if you did everything correctly, the crankshaft should be on the mark when you shine the light down there...Remember, it is not right at the top, it is off to the left of center...
The next thing to check is the fuel injection fuse...It is a 25 amp blade type fuse located on the left fender just behind the battery...It is a bad location and it gets corroded...
When you replaced the belt, what did you use to keep the crank shaft from turning so that you could remove the center bolt on the pulley/harmonic balancer?...
Jerry
I would re-check the belt timing...The diagram supplied by Kmaniac is where it should be...You will need to remove the upper belt cover to check it and you should be able to see the lower mark with a strong flashlight without removing the crank pulley and lower cover...Line up the camshaft mark at the top and if you did everything correctly, the crankshaft should be on the mark when you shine the light down there...Remember, it is not right at the top, it is off to the left of center...The next thing to check is the fuel injection fuse...It is a 25 amp blade type fuse located on the left fender just behind the battery...It is a bad location and it gets corroded...
When you replaced the belt, what did you use to keep the crank shaft from turning so that you could remove the center bolt on the pulley/harmonic balancer?...
Jerry
hey jerrymcc,
thanks for sticking around. i'm including pics for your reference.concerning the pulley harmonic balancer - i just held it in place no special tool used. i think that it should not be that difficult to set timing with out any special tool, but i may be wrong.
concerning the fuel injection fuse. when I ran the codes for fuel injection I got a 1-1-1 which normally means all is good with fuel injection no? do you have a pic of the fuse. i looked next to the battery and can't find it.
Also, one thing i noticed which i mentioned a few posts back but did not get any feed back on, was that i am not getting a spark when i ground spark plug cable #1 to make sure their is 'juice' coming thru. any thoughts on this?
thanks.
thanks for sticking around. i'm including pics for your reference.concerning the pulley harmonic balancer - i just held it in place no special tool used. i think that it should not be that difficult to set timing with out any special tool, but i may be wrong.
concerning the fuel injection fuse. when I ran the codes for fuel injection I got a 1-1-1 which normally means all is good with fuel injection no? do you have a pic of the fuse. i looked next to the battery and can't find it.
Also, one thing i noticed which i mentioned a few posts back but did not get any feed back on, was that i am not getting a spark when i ground spark plug cable #1 to make sure their is 'juice' coming thru. any thoughts on this?
thanks.
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Retired MVS Contributor
Photo # 2 concerns me...I don't see an arrow on the crankshaft toothed sprocket...There should be an arrow on the front face of that sprocket...The crankshaft might be out by 180 degrees, but we cannot see the lower side because it is hidden in the photo...The crankshaft toothed sprocket has 2 keyways on it and one of the keyways is in line with arrow and the other one is 180 degrees out...You did not use the keyway as your mark, I hope...If you did, and if the arrow is at the bottom in that photo, then you need to line up the cam gear on it's mark, remove the belt, rotate the crankshaft 180 dergrees, then reinstall the belt...
The reason I asked about how you held the pulley while you loosened the center bolt on the harmonic balancer is because if you held it by the outer surface of the pulley, you could have torn the pulley loose from the hub...The pulley and the hub are separated from each other by a rubber insert...It will have no effect on the belt timing, but it will affect the ability to time ignition later...You should never need to time the ignition, it is a set-and-forget operation, but the pulley can slip on the hub and mess up alternator charge and A/C, and in really bad slipping can cause overheating...
A fellow I knew years ago held the pulley with a strap wrench and separated the hub from the pulley...The hub has 3 spokes and the correct holding tool grabs those spokes, not the pulley...
I am a little confused by what you said about "grounding spark plug cable #1"...Grounding the cable directly to the engine will not produce a spark, you need some kind of air gap between the cable and the engine...The best way is to connect the cable to a spark plug then ground the threaded base of the spark plug to the engine...You should see a spark jump the gap of the spark plug...
Jerry
The reason I asked about how you held the pulley while you loosened the center bolt on the harmonic balancer is because if you held it by the outer surface of the pulley, you could have torn the pulley loose from the hub...The pulley and the hub are separated from each other by a rubber insert...It will have no effect on the belt timing, but it will affect the ability to time ignition later...You should never need to time the ignition, it is a set-and-forget operation, but the pulley can slip on the hub and mess up alternator charge and A/C, and in really bad slipping can cause overheating...
A fellow I knew years ago held the pulley with a strap wrench and separated the hub from the pulley...The hub has 3 spokes and the correct holding tool grabs those spokes, not the pulley...
I am a little confused by what you said about "grounding spark plug cable #1"...Grounding the cable directly to the engine will not produce a spark, you need some kind of air gap between the cable and the engine...The best way is to connect the cable to a spark plug then ground the threaded base of the spark plug to the engine...You should see a spark jump the gap of the spark plug...
Jerry
hey jerrymcc,
I held the pulley using a small socket. Not clear from the picture - you're right. And i understand the issue about testing the wires and the gap needed - thanks there as well.
Actually i got the car started. interesting though I used the old crank shaft positioning sensor. The new one just did not want to work. ( I ran the codes and got a 2-1-4 code remember)
I have other issues though that i can use you help with. these issues existed before the timing issue. in fact that is why i started messing with the timing cuz i thought that would fix the original issues.
1. the vehicle losses power, wants to stall, at 15-20 mph and then again at 50 mph. in fact it has completely turned off at 55-60 mph at times.
2. the overdrive gear will at times not engage at all and other times it will.
3. this one is most recent - i am not able to properly reset the OBD unit. i have followed the instructions, pretty straight forward, but can't reset it. ( unit still stuck on 2-1-4 code - and yet vehicle did turn on - confusing ).
Any suggestions are most welcomed.
I held the pulley using a small socket. Not clear from the picture - you're right. And i understand the issue about testing the wires and the gap needed - thanks there as well.
Actually i got the car started. interesting though I used the old crank shaft positioning sensor. The new one just did not want to work. ( I ran the codes and got a 2-1-4 code remember)
I have other issues though that i can use you help with. these issues existed before the timing issue. in fact that is why i started messing with the timing cuz i thought that would fix the original issues.
1. the vehicle losses power, wants to stall, at 15-20 mph and then again at 50 mph. in fact it has completely turned off at 55-60 mph at times.
2. the overdrive gear will at times not engage at all and other times it will.
3. this one is most recent - i am not able to properly reset the OBD unit. i have followed the instructions, pretty straight forward, but can't reset it. ( unit still stuck on 2-1-4 code - and yet vehicle did turn on - confusing ).
Any suggestions are most welcomed.
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Retired MVS Contributor
I've been re-reading this thread and realize that my age (80) caught up with me in a previous post...I told you to check the fuel injection fuse as located in a 240, forgetting you had a 740... 
The fuse in the 740 is located behind the ash tray and is probably not an issue here, but the injection relay might be bad, and will not necessarily throw a fault code...The relays can get intermittent...Most folks replace them, but they can be opened up and resoldered...Fractured solder joints are common and the cracks can be seen with a magnifier or jeweler's loupe...The relay is behind the ash tray too, second row, left side...
You said you cannot erase the 2-1-4 code...Do you mean that you cannot erase it at all, or that you can erase it but as soon as you start the engine the code comes right back...If that is what is happening (it keeps coming back), it is because the cause of the fault is not being fixed...But if you cannot erase at all, it means there are other problems, possibly with the flashing code reader unit itself, or, maybe the control unit...There are step-by-step procedures for testing the system components by disconnecting the control unit and checking each and every wire and component with a volt-ohm meter...It is a long, drawn out procedure that I do not have the space or time to send...It will fill a small book...
Where did you buy the replacement crankshaft sensor?...Is it original equipment or a generic replacement...Stick with OEM with Volvo...If it is generic, I would try to get my money back since it does not work but the original does...
It is very difficult to analize problems from afar and the best I can do is make suggestion as to what to try...Good luck...
Jerry
The fuse in the 740 is located behind the ash tray and is probably not an issue here, but the injection relay might be bad, and will not necessarily throw a fault code...The relays can get intermittent...Most folks replace them, but they can be opened up and resoldered...Fractured solder joints are common and the cracks can be seen with a magnifier or jeweler's loupe...The relay is behind the ash tray too, second row, left side...
You said you cannot erase the 2-1-4 code...Do you mean that you cannot erase it at all, or that you can erase it but as soon as you start the engine the code comes right back...If that is what is happening (it keeps coming back), it is because the cause of the fault is not being fixed...But if you cannot erase at all, it means there are other problems, possibly with the flashing code reader unit itself, or, maybe the control unit...There are step-by-step procedures for testing the system components by disconnecting the control unit and checking each and every wire and component with a volt-ohm meter...It is a long, drawn out procedure that I do not have the space or time to send...It will fill a small book...
Where did you buy the replacement crankshaft sensor?...Is it original equipment or a generic replacement...Stick with OEM with Volvo...If it is generic, I would try to get my money back since it does not work but the original does...
It is very difficult to analize problems from afar and the best I can do is make suggestion as to what to try...Good luck...
Jerry
thanks jerrymcc,
I did get a generic sensor and was able to return it.
yes, I erase the code but it comes back.
I will look into the injection relay as you suggested. do you have a pic of it?
What about the overdrive gear engaging and not engaging? You think it is related to the injection relay as well?
*One thing I failed to mention was that the lose of power seems to be to the #1 spark plug cable only. I connected a timing lamp to the cables and noticed that the timing light stops flashing on the #1 cable between 1500 - 2000 rpms. don't know if this means anything to you.
I did get a generic sensor and was able to return it.
yes, I erase the code but it comes back.
I will look into the injection relay as you suggested. do you have a pic of it?
What about the overdrive gear engaging and not engaging? You think it is related to the injection relay as well?
*One thing I failed to mention was that the lose of power seems to be to the #1 spark plug cable only. I connected a timing lamp to the cables and noticed that the timing light stops flashing on the #1 cable between 1500 - 2000 rpms. don't know if this means anything to you.
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lummert
- Posts: 1381
- Joined: 29 January 2008
- Year and Model: 760 1988
- Location: Portland Indiana, USA
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When was the last time that the distributor cap, rotor and plug wires were replaced? A bad plug wire can cause a misfire at the RPM that you mentioned.
1988 Volvo 760 Turbo Wagon
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