No acc. power,but truck runs?

[NOTABLAZER]

Here's a good one,I was driving my '91 today,I had planned to take it through the wash before I "put it away" again. I was driving along and all of a sudden the radio just shuts off all by itself. I'm thinking "that's odd" and reach over to try and turn it back on,when I realize none of the dash lights seem to be on either. So at this point I pull over,and after realizing none of the lights are working either,I decided to high tail it back home before it got dark.

The truck starts and runs fine,but literally nothing else electrical is working EXCEPT the oil pressure light will pop on before you turn the key to start,and the brake warning light stays on. Any ideas? The truck is a stripper model too if it matters.

 

[Simplysmn]

check your fuseable link's or ground's

 

[Moe]

Try the crank speed sensor. If it goes bad then the the truck thinks its not running, but will run just fine minus any electrics. Moe

 

[HHhuntitall]

I'd wager on the fusible link, myself. Even if the Crank Speed Sensor goes bad, you should have lights..... I think it's one of the outside ones, on the three wire connector. Also, check to make sure you don't have any corrosion where that wire connects to the battery terminal. I've fixed a great many that have lost connection there. Age and lead acid do a number.

 

[NOTABLAZER]

Does my truck even have the crank speed sensor? I did the KDP fix last year and the instructions mentioned it but once i dug into the truck I found that there wasn't even one on there. I assumed it had something to do with the non-inter-cooled aspect. I guess I have some checking to do,and this always seems to happen when it's cold as hell out there

 

[Moe]

Front of engine. Looking down at the balancer. Follow the 2 wires down and it will be there. Moe

 

[Moe]

when I replaced mine I used a brass feeler gauge to set the gap. Moe

 

[Paychk]

I believe the early 91's don't have the crank sensor, that came when the factory turbo was added.

 

[DVolk]

Ive heard that crank sensor is only for cruise controll

 

[Paychk]

Also turns on the alternator, a/c, and cruise control (I think)

 

[HHhuntitall]

I beleive tach sensor function didn't begin to regulate voltage and A/C function until late '92. If you have a voltage regulator on the firewall, the tach sensor is optional, I believe, and not connected. Most engines have it mid '91 and later, and any prior that had the Mopar tach installed in the truck. transmission regulation is controlled by the TPS on autos..... Manual Gutrott, err, I mean Getrags, require a short circuit behind the steering wheel to shift properly.

 

[Paychk]

I believe 91. 5 is when the PCM and crank sensor came online:

https://www.turbodieselregister.com...993/204746-crankshaft-sensor.html#post2196419

 

[Bob Beauchaine]

My neighbor has a 91. 5 D350 SRW and it has a voltage regulator. I went with him when he looked at it. It was an old GTE pick-up and it has no bells or whistles and had less than 100k on the speedo. I did see the voltage regulator on the firewall and also it had a new Cummins IP - I felt it was part of the IP recall. It is a baged D350 with a heavy duty spring pack.



Bob

 

[HHhuntitall]

I've got a '92 in my shop right now..... it was built post 91. 5..... and it has a voltage regulator on the firewall. That's why I got it so cheap in fact, the local parts guys had repeatedly given the previous owner the wrong regulator. I plugged in the new one, and the alternator immediately starting pulling the motor down, so I knew it was fixed. Quick check with the volt/amp meter/tester, and I could move on to something else that is wrong with this truck..... like no brake lights... . busted out door hinge..... no front driver side turn signals... . sagging front springs... . u-joint... ... Wait!!! What was my New Year's resolution again?!?!!?

 

[TIngersoll]

Sounds like the problem Ive been fightin for two years on and off, also. Very interested to see if you figure it out. Got me trying to get mine inside and go at it again. Oo.

 

[HHhuntitall]

After checking the fusible links, also check the main power feed that goes inside to the fuse box. Pull your fuse panel and check the back side for any green looking corrosion or black burned spots. If the main feed wires burn in to here, you won't get anything downstream, naturally. I haven't seen that but once; it looked like the feed wire overheated at the box, and when it cooled, it corroded with the moisture in the air. Took time, but it eventually quit, and I had to splice the wire and resolder it in the box..... A test light would quickly tell you if you had any fire behind or in front of the fusible links.....

 

[NOTABLAZER]

OK,here's an update...



It runs,and the problem was the stupidest thing. I had some daylight today and it wasn't too cold out today,so i thought I'd check the engine bay again,and at least jiggle some wires around



I pulled the headlight switch,and started looking around under the hood. I noticed a wire that went from the core support to the negative battery terminal,and the end was pulled out from the terminal. I thought to myself "no way that's all it was" and touched it to the negative terminal,and all of a sudden the lights flipped on.

 

[Dale Reed]

Sorry to be kinda off thread but do any of you know what the Amps are for each of fusible links on the left fender? Thinking of replacing one of them that has lost most of its insulation.

 

[Paychk]

The sizes of the fusible links are determined by the color of the link's insulation. This is the chart from the FSM:

12 Ga. Black
14 Ga. Red
16 Ga. Dark Blue
18 Ga. Gray
20 Ga. Orange
22 Ga. White

I believe the gauge # listed is the size of the link, more info can be found here:

Electrical Issues - MiniMopar Resources

 

[Dale Reed]

Thanks Paychk, but I want to know the Amps not the wire gauge, whatever that means. Are these the gauges of the wire that will be protected by fusible links or any other kind of fuse? Also what does "FSM" mean?



Also, if you or anyone else, can tell me where this information is in the 1990 Service Manual?