Coolant level sensor

[nico1277]

Hello,
I reinstalled the coolant level sensor in my CUCV and connected the cable. After that the engine started shortly afterwards it went out and did not start anymore. After I unplugged the cable, it started normally again. Can someone tell where the problem is?
Greetings from Germany

 

[cucvrus]

never heard that one before. Are we talking the low coolant sensor at the right side of radiator? Or are you talking the temp sensor on the front left head. I seen this happen when the coolant temp sensor was hooked to a glow plug and the front glow plug wire hooked o temp sensor. Please clarify. Pictures of wire that you are speaking of please.

 

[nico1277]

never heard that one before. Are we talking the low coolant sensor at the right side of radiator? Or are you talking the temp sensor on the front left head. I seen this happen when the coolant temp sensor was hooked to a glow plug and the front glow plug wire hooked o temp sensor. Please clarify. Pictures of wire that you are speaking of please.

yes, the one to the right of the radiator.
the vehicle has been converted to manual preheating. maybe it has something to do with it.

I'll send pictures tomorrow.

 

[nico1277]

so here is the photo of the plug that causes the problems.

It was connected to the coolant level sensor on the right side of the radiator and nothing worked.

 

[Barrman]

The wire for that sensor runs with the headlight wiring around the front of the truck. The pink wire that turns on the Injection pump comes down the valve cover and over the rear of the engine. Basically, they don't come within a few feet of each other. So, the level sensor shorting out the IP power just doesn't add up.

Except at the firewall plug where all the wires are together. My suggestion is to use a 10 mm socket and unbolt the firewall plug. Remove the engine side and see if any of the blades are bent over or something else weird inside there. That is all I can think of for a stock wiring set up.

However, you have a modified wiring system at least with the glow plugs. What else was messed with?

 

[nico1277]

The wire for that sensor runs with the headlight wiring around the front of the truck. The pink wire that turns on the Injection pump comes down the valve cover and over the rear of the engine. Basically, they don't come within a few feet of each other. So, the level sensor shorting out the IP power just doesn't add up.

Except at the firewall plug where all the wires are together. My suggestion is to use a 10 mm socket and unbolt the firewall plug. Remove the engine side and see if any of the blades are bent over or something else weird inside there. That is all I can think of for a stock wiring set up.

However, you have a modified wiring system at least with the glow plugs. What else was messed with?

Yes you are right, the previous owner played around a lot with the electronics, there must have been a cable fire, after that everything was only repaired temporarily. Everything important works fine. I think if everything is to be perfect, the entire electrical system has to be new. But I can't do that alone, I have to seek help. Let's see what I can do there.

 

[rmesgt]

You have to eat an elephant one bite at a time. I would suggest that you start with the front of your CUCV. There is a wire harness that runs from the drivers side (DS) firewall, across the DS fender to the front of the truck. At this point, the wires branch to provide power to the DS Headlight (Lt Green, Tan, Black), DS Side Marker (Brown and Black) and DS BO marker (Brown w/ White Chaser and Black). The horn wire and the BO headlight wire stop at this point. All other wires continue to the Passenger Side (PS) side of the truck. These wire are inside a loom that runs underneath the vehicle grill. The easiest way to access this loom is to remove the headlight bezels and the grill. Inside the loom is a bundle of wires. One of these wires is BLACK W/ YELLOW CHASER. This is the wire that attaches to the Low Coolant Sensor. The other wires previously discussed go to their respective components (Headlight, Side Marker, BO Marker, Ground). The BLACK W/ YELLOW CHASER wire runs from the radiator sensor to the low coolant module. I do not know where the Low Coolant is located. CUCVRUS knows everything. He can point you to the module. Once you locate the module, you should be able to check for continuity between the end of the wire at the sensor and the end of the wire at the low coolant module. This should let you know if you have a break in the wire. If the wire is good, then you have to check the low coolant module. If the module is good, you have to go upstream from there. I believe the low coolant module gets it power from Fuse #17.

 

[nico1277]

You have to eat an elephant one bite at a time. I would suggest that you start with the front of your CUCV. There is a wire harness that runs from the drivers side (DS) firewall, across the DS fender to the front of the truck. At this point, the wires branch to provide power to the DS Headlight (Lt Green, Tan, Black), DS Side Marker (Brown and Black) and DS BO marker (Brown w/ White Chaser and Black). The horn wire and the BO headlight wire stop at this point. All other wires continue to the Passenger Side (PS) side of the truck. These wire are inside a loom that runs underneath the vehicle grill. The easiest way to access this loom is to remove the headlight bezels and the grill. Inside the loom is a bundle of wires. One of these wires is BLACK W/ YELLOW CHASER. This is the wire that attaches to the Low Coolant Sensor. The other wires previously discussed go to their respective components (Headlight, Side Marker, BO Marker, Ground). The BLACK W/ YELLOW CHASER wire runs from the radiator sensor to the low coolant module. I do not know where the Low Coolant is located. CUCVRUS knows everything. He can point you to the module. Once you locate the module, you should be able to check for continuity between the end of the wire at the sensor and the end of the wire at the low coolant module. This should let you know if you have a break in the wire. If the wire is good, then you have to check the low coolant module. If the module is good, you have to go upstream from there. I believe the low coolant module gets it power from Fuse #17.

Thank you very much, I'll do it like this. The module should be on the steering column. I had already seen. I haven't checked that with the Fuse.
Thanks for the advice.

But why is the motor switched off when the cable is connected and runs when it is disconnected.

 

[rmesgt]

Thank you very much, I'll do it like this. The module should be on the steering column. I had already seen. I haven't checked that with the Fuse.
Thanks for the advice.

But why is the motor switched off when the cable is connected and runs when it is disconnected.

I am not certain, but lets ponder.... The "Low Coolant" sensor is nothing more than a switch. If the switch is open (not connected to ground), nothing happens at the instrument cluster. If the switch is closed (completing the ground), the instrument cluster light illuminates. Knowing this, understanding what you stated AND providing that the radiator is full, we can ascertain that the "Low Coolant" sensor is broken, maintaining a completed ground at all times. If this is the case, this "ground" may be shutting down other controls that have somehow been linked to the "Low Coolant" module. I make this assumption because when the wire is connected to the sensor, the engine quits running. When the wire is disconnected from the sensor, the engine runs well. The difference is if the wire IS or IS NOT connected to the sensor. If the wire IS NOT connected, there is no way for the ground to occur and the engine works. When the wire IS connected (possibly completing the ground) the engine fails.

OR

B. The "Low

 

[nico1277]

I am not certain, but lets ponder.... The "Low Coolant" sensor is nothing more than a switch. If the switch is open (not connected to ground), nothing happens at the instrument cluster. If the switch is closed (completing the ground), the instrument cluster light illuminates. Knowing this, understanding what you stated AND providing that the radiator is full, we can ascertain that the "Low Coolant" sensor is broken, maintaining a completed ground at all times. If this is the case, this "ground" may be shutting down other controls that have somehow been linked to the "Low Coolant" module. I make this assumption because when the wire is connected to the sensor, the engine quits running. When the wire is disconnected from the sensor, the engine runs well. The difference is if the wire IS or IS NOT connected to the sensor. If the wire IS NOT connected, there is no way for the ground to occur and the engine works. When the wire IS connected (possibly completing the ground) the engine fails.

That's right, but then doesn't the control light on the dashboard have to light up? It's completely dead. But it works, I've cleaned the instrument panel and tested all the lamps.

 

[Barrman]

The above listing of a ground sequence is why I wrote about how the coolant wire doesn't ever get within a few feet of the IP power wire yesterday.

I think you will end up finding a messed up thru firewall plug pin or two, some wires missing insulation that are touching or since you mentioned burnt wiring. A melted mess of wires somewhere under the dash.

I would suggest you download the -20 manual and print out each of the schematic wiring diagrams. Remove the gauge cluster, unplug the thru firewall plug and follow every wire visually and use an Ohm meter to verify continuity of each and every wire.

 

[nico1277]

The above listing of a ground sequence is why I wrote about how the coolant wire doesn't ever get within a few feet of the IP power wire yesterday.

I think you will end up finding a messed up thru firewall plug pin or two, some wires missing insulation that are touching or since you mentioned burnt wiring. A melted mess of wires somewhere under the dash.

I would suggest you download the -20 manual and print out each of the schematic wiring diagrams. Remove the gauge cluster, unplug the thru firewall plug and follow every wire visually and use an Ohm meter to verify continuity of each and every wire.

That's right. i will do this as the last task. First of all, the frame and the sub-floor must be derusted and preserved. Then the brake lines are new and in October the CUCV has to go through the TÜV (I hope you know what that is). When that's done, I'll have my head free for the electrics.

 

[nico1277]

Hello from Germany,
I have now started renovating the electrical system in my CUCV m1008.
Now I have a question, can someone tell me how many amps are going through the starter relay? How strong does this relay have to be? Since this relay should also be exchanged, unfortunately there is nothing on it.