2nd Gen Non-Engine/Transmission ABS, BRAKE, & Airbag light come on, blower fan, speedo, power windows become inop intermittently

[Chief USA]

PCM/ECM test shows P0500 & P1693. I have a rear axle abs sensor replacement on order. Spoke with a friend who had this problem on his 2nd Gen truck but he did not remember the issues with the blower fan and power windows?

On initial start up, if I recycle the ignition switch and let it self test until it finally passes, everything works great until the abs, brake, & airbag light come on again on the next start up.

I will be troubleshooting some connections and looking at the abs and some other fuses as well.

I tried doing a forum search and found only a single instance of this here:

https://www.turbodieselregister.com...trical-problem-need-help.242159/#post-2342230

The thread was locked and the op has not been on the website since 2018. Has anyone else encountered this problem? If so, what did find to be the problem & fix. Thanks in advance & Merry Christmas to all!

 

[brucejohnson]

Chief USA, Initial trace for the power circuits show the power windows, blower fan and ABS all are powered through the same ignition switch contacts: BATT A2; contact 2 (Run); plug C1 pin 5, feeding Junction Block Power Window CB 1, Blower Motor Relay Fuse 2 and Controller Antilock Brake Fuse 3. Still looking into the speedometer circuitry. I thought I saw where one of the affected fuses control the PCM B+ voltage.
One area to check before digging too deep is each of the battery's wires; especially the smaller ones that are attached to both positive and negative battery terminals.

 

[Chief USA]

I didn't notice anything else that went inop. at the time. Tach, oil pressure, lights, turn signals all work fine. Just those things that I have already mentioned. Didn't time to do any troubleshooting today, getting ready for quests and had one last haul of firewood to get out of the woods before we may get some snow this week. It is a weird & intermittent thing, while driving over to farm to get the firewood, everything started working normal again but once I shut the engine off, it went right back to the same problems.

 

[brucejohnson]

Do you have a heavy set of keys hanging from your ignition switch. Years ago, my sister's car was having intermittent electrical issues. It came down to her huge key collection on her key ring basically wore out the switch tube and contacts after 200,000+ miles on her 74 Dodge Aspen wagon.

 

[Chief USA]

No. Just the ignition key, fob, and a steering wheel lock key.

 

[brucejohnson]

Try jiggling the key in the run position to see if the symptoms come and go.
While the problem is evident you can also check for voltage on fuses 2, 3, 7, 18 and CB 1 in the Junction Block. These are fed by the suspect contacts in the ignition switch.
Fuse 2 = Blower Motor Relay
Fuse 3 = Antilock Brake Controller
Fuse 7 = Backup Lamps
Fuse 18 = Airbag Control Module
CB 1 = Driver and Passenger Power Windows

 

[Chief USA]

After MUCH observing the behavior of this problem, I think I have found the culprit. It is the ignition switch. If I turn the ignition switch from the ON//RUN position just a hair towards the off position but not enough to shut the engine off or cause the dash lights to go out, everything comes back on and works properly. I strongly suspect something inside the ignition switch has slipped or become oxidized causing the missed electrical connection. At first, I had a terrible time trying to reproduce the conditions & problem and what temporarily fixed it. Now I can get everything to work everytime by doing this. I will be replacing the ignition switch. Now I need to figure out which brand is the best to get. So far, my choices on Rock Auto are Wells Vehicle Electronics, Standard Motor Products, and Rostra Power Train Controls. I am leaning towards Wells Vehicle Electronics but I need to do more researching on ignition switches. Autozone offers a limited lifetime warranty on their Duralast ignition switch which I may go with since they are closer and the best warranty. The genuine Mopar switch comes with a 30 day warranty. Anyway, figured I would post this in case anyone else is chasing their tail with this problem.