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No crank no start

Tiny
RBRO533
  • MEMBER
  • 1997 DODGE CARAVAN
  • 3.8L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 170,000 MILES
The van started okay, let it warm up for a couple of minutes. Then put it in reverse backed up a few feet then it shut off. When I went to restart it I had a no crank no start problem. Checked the battery it was okay, but tried a jump start anyway but nothing. Checked the fuses and relays even swapped out the relay just in case still nothing. Checked that the starter is getting power and it is gave it a few taps and still nothing. If you put a jumper wire across pins 30 and 87 the starter will work but engine will not start and that is with the key held in the full start position. If the key is in full start position with the lights on the lights do not dim at all. While it was running the only thing done was the MAP sensor was replaced and the van was started and run numerous times since then. I know some basics about cars but if suggestions of things to try could be put in very basic and detailed directions I would really appreciate it. Thanks
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Saturday, July 7th, 2018 AT 9:55 AM

29 Replies

Tiny
STEVE W.
  • MECHANIC
  • 12,958 POSTS
The description sounds like a failed ignition switch or the park/neutral switch. Try shifting it into neutral and wiggling the shift lever while holding the key in start. If that gets nothing then you will need to do some testing at the starter relay to see if there is power and ground to the starter relay. Attached you will find the starting circuit schematic.

If you have a test light handy you can test the circuit easily. First be sure that the battery cable connections are clean and tight at both ends, have seen many no crank issues caused by a failed battery cable. Then take the test light connected to ground and turn the key to start while touching the test light tip to terminal 86 in the starter relay socket. If the light comes on the switch is working and the fuse and the 3A circuit breaker is okay. If the light does not light, pull the circuit breaker and test on both terminals for power with the key in start. There should be power on one side. The other sends power to the relay. If you find power there but not in the relay socket, the breaker may be bad. To test if it is the breaker or the wiring just probe the power terminal in the relay socket and use a jumper in place of the circuit breaker. If you have power at one side of the breaker and install a jumper and still do not have power in the relay socket the wiring is open.
If you find power on terminal 86 with the key in start, release the key, then connect the test light to battery positive. Touch terminal 85 and hold the key in start. If the light comes on the PCM is supplying the ground. If no light then you need to see if there is a ground at the PCM itself with the key in start. If there is then the wire between the PCM and relay socket is bad.
Do those tests and see what you find. Post back with the results please.
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Tuesday, July 10th, 2018 AT 11:49 AM
Tiny
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Battery and cables checked out. Checked pin 86 and test light came on. Checked pin 85 and no light. You said to check the ground at the PCM, where should I check that at? Do I back probe the wire that comes from pin 86 to the PCM harness or is there a way to check the PCM ground in general? I am somewhat familiar with working on cars but, thank goodness, I have not ever really had to deal with electrical problems so it is not my strong point. So, where do I go from here?
Thank you for your help!
Renee
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Wednesday, July 11th, 2018 AT 5:26 PM
Tiny
STEVE W.
  • MECHANIC
  • 12,958 POSTS
If you do not have a ground at pin 85 with the key on then go to the PCM harness and check continuity from pin 8 in connector 1 to pin 85. If that works then either the PCM is not receiving the crank signal through the transmission control module and it does not switch the ground on, or the PCM is bad. However based on your symptoms I am going to guess it is an issue with the neutral safety switch/range sensor not operating correctly.

It is a convoluted system in the way it works. You turn the key to start. The battery voltage gets to the starter relay and stops. The leg going to the transmission control module wakes it up and it looks at the inputs from the neutral switch. If it shows park/neutral then it tells the PCM that it is okay to start the car. The PCM then grounds the relay and the engine turns over.

The testing you did shows the voltage switching to the relay is good. Now we need to verify the signal through the transmission module and "range sensor" is working.

One way to also verify that the wiring is okay would be to use a jumper wire from pin 85's wire (dark blue/orange stripe or tan wire) to ground. If turning the key now cranks the engine (might even start up with that ground) you have an issue in the switch or wiring on the transmission side (more likely the switch)

For that we will start with fuse 2. It provides the power to the range sensor through the TCM. The switches are cheap compared to the time it takes to test them. Yours should be the one in the middle. The other one is the early build with the three speed trans. Rather than testing each circuit I would install a new switch and go from there. The connectors and switches are both failure prone.
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Wednesday, July 11th, 2018 AT 6:48 PM
Tiny
RBRO533
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I did do a continuity test from relay pin 85 to pin 8 at PCM connection and it did have continuity. I also tried putting it in neutral and wiggling the shifter while trying to start it and no change there. I will try the jumper wire to pin 85 and see what happens. I had previously checked all fuses and 2 is good. Now, forgive my ignorance but you say replace the switch but you talk about the TCM, range sensor and park/neutral switch. Are you saying when I try the jumper wire and if it works that I should replace the neutral switch? What if anything should I do or test on the TCM or range sensor?
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Wednesday, July 11th, 2018 AT 8:26 PM
Tiny
STEVE W.
  • MECHANIC
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The range sensor/neutral switch are the same part. The main reason I suggest replacing it is simply because they are failure prone and you can remove and replace it in less time than it takes to test it.
However you can test it if you wish. The first schematic has the pin outs and in park/neutral it should have a ground on the black wire with white stripe. The ground should go away in all other gears.
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Wednesday, July 11th, 2018 AT 9:42 PM
Tiny
RBRO533
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I put a ground to pin 85 and turned the key to start and it tries to start. So is that going to be the neutral safety switch? If so it will probably be tomorrow before I can get the part and then put it on. Now if we have that taken care of I need to pick your brain on a problem the van had before it quit starting. The cooling fans run from the time you start the car even with the A/C off and the temperature gauge stays at cold, any ideas? The cooling fan relay had been replaced and the temperature sensor replaced as well. Sorry for the extra question but you have been so helpful I hate to lose you by starting another thread, unless I have to. Your time and effort is very much appreciated especially since my financial situation is pretty diré right now.
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Thursday, July 12th, 2018 AT 11:24 AM
Tiny
STEVE W.
  • MECHANIC
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PTC 10 is a self resetting thermal fuse, works like a circuit breaker but for smaller loads. The junction block is under the hood and should resemble the image below.
No problem, we are here to help if possible.
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Thursday, July 12th, 2018 AT 12:51 PM
Tiny
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Okay, the neutral safety switch that you referred too, which is the middle picture, looks like what I have. Now the big question, because I cannot seem to find a good reference, how do you replace it? It does not look as though it is as easy as the other one which screws out and then in, just my luck. I could really use some help with this.
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Friday, July 13th, 2018 AT 9:25 AM
Tiny
RBRO533
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Just so you have all the information. I have also noticed that the van will try to start in any position. Also the circle that indicates what gear you are in sometimes is around all the letters and sometimes it will be around the one you want. I imagine those problems also indicate a bad switch. From what little I have gathered I am going to have to take a cover off the transmission which will lose some fluid. Do I drain some first or just have pan under the cover? After that I still need a step by step tutorial or video if at all possible.
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Friday, July 13th, 2018 AT 11:42 AM
Tiny
STEVE W.
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Yeah that sounds like a bad switch or the wiring harness has a problem. Check it close, especially where it gets close to brackets or other parts.

Replacing it You need to remove the pan, which means you will lose most of the trans fluid. So this would also be a good time to replace the filter and fluid. Then you need to remove the transmission manual shift lever from the shift shaft, then drop the pan and filter, shift the transmission into low at this point to get the park roller out. Then unbolt the transmission valve body.
Reverse the process to put the new one in. (that is what the book has)
What it does not say is that they did this on a transmission that was out of the vehicle. The valve body actually has springs and pistons and a few other parts that can come out when you do this as you will be pulling it down.
I believe that is because only the 1997 and early 1998 uses the switch like you have. The rest use the exterior mounted switches.

There are a few videos online showing the 41TE unit you have if you watch them you can get a better idea of what you will be doing.

https://www.youtube.com/watch?v=KxXu8jf1s9E
https://www.youtube.com/watch?v=sL_-T2ZSc_g
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Friday, July 13th, 2018 AT 2:48 PM
Tiny
RBRO533
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Yeah, like you said while in there might as well replace them. So I went ahead and bought a new filter, seal and fluid. I am going to try to get at this tomorrow (Saturday). Will you be available for questions? I hope I will not have any but replacing the switch will be a first.
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Friday, July 13th, 2018 AT 6:26 PM
Tiny
STEVE W.
  • MECHANIC
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I would watch a few of the videos and before you tear into it check the outer wiring harness really close. Would no like for you to take it all apart to discover it is just a bad wire outside the transmission.

Also, you said it will try to start in every position? So it is cranking over now? If it is cranking over but not starting the most common failure item is the crank position sensor.
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Friday, July 13th, 2018 AT 10:01 PM
Tiny
RBRO533
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I unplugged the wire harness at the switch and did a continuity test on the wire (black/white) to the PCM and it was good. I also used some wire cleaner and cleaned up the connections. I will check a little more just to try and make sure it is not the wiring. On the crank but no start it may be the crank position sensor, could it be the reason for the not cranking in the first place or is it still most likely the neutral safety switch (and or wiring)? Also, since this problem started the van has been sitting for a couple of weeks while trying to figure out the no crank problem, could the sitting up be why it will not start right up. As I said when this first happened, it started right up that day then when I put it in reverse it shut off and would not crank or start again until you suggested the jumper wire to pin 85. What would be the odds of the safety switch and crankshaft sensor having gone out at the same time? Just FYI, the crank and cam sensors were replaced two years ago. Any more ideas or suggestions before the switch has to be done?
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Saturday, July 14th, 2018 AT 3:40 PM
Tiny
STEVE W.
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The transmission switch can easily be the no cranking problem.
The crank position sensor would not cause it to not turn over, it will cause loss of spark and not starting though.
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Saturday, July 14th, 2018 AT 6:58 PM
Tiny
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Okay then, I will give the wiring a good once over and if I do not find anything that will get it cranking I will go ahead and replace the switch. After I replace the switch if I still have a starting problem I will change the crank sensor for the second time in two years. If I have any questions along the way I will send a message.
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Sunday, July 15th, 2018 AT 9:16 AM
Tiny
RBRO533
  • MEMBER
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One more thing; I have also noticed that the steering wheel is not locking, is that related to the switch as well? I would think so but want to be sure.
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Sunday, July 15th, 2018 AT 12:36 PM
Tiny
STEVE W.
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The wheel should only lock with the transmission in park, if the system does not think it is in park it will not lock.
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Sunday, July 15th, 2018 AT 4:01 PM
Tiny
RBRO533
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I replace the range sensor and it still will not crank. I put the jumper wire on pin 85 again and it will crank then. It still tries to crank in any gear as well and the steering wheel still will not lock. The gear selector light still has all gears highlighted also. Any suggestions?
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Monday, July 16th, 2018 AT 4:06 PM
Tiny
STEVE W.
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If it is not seeing the range sensor there is either an internal wire break in the harness or a failure in the TCM.
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Tuesday, July 17th, 2018 AT 9:16 PM
Tiny
RBRO533
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I was not able to do anything for a few days but back at it. When the range sensor was put in how do you know if the park rod is inserted correctly into the park sprag/prawl? Just to be sure, which way should the rod be turned so the rollers are in correctly? When I have the whole unit up with just a slight crack to see inside the rod end is just inside the other side. I had read some people saying something like when the rod "engages", how is that done or how do you know if it has? I have done some more checking on some wires and harnesses and have not found anything but as old as this van is it might just be that I have not found it if that is the problem. I think right now I need to make sure I have the rod seated correctly because if I do not think the van would know if it is in park, is that correct? Also, could the ignition itself, not the switch since there is signal to the PCM, cause the no crank or would that problem have presented itself with a problem I am not having?
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Saturday, July 21st, 2018 AT 3:26 PM

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