M38a1 dash hook up for Wes question

Shug4 · Post by **Shug4** » Mon May 28, 2018 7:18 pm

Wes I have m38a1 electrical problems. This is going to be a long one. First no juice to light switch at all. I have an ignition switch that has 4 wires coming from it labeled A,B,C and D. A and C are hooked together going to hot wire. D is hooked to 12 and B has 2 wires coming out from it labeled 85 and 27. 27 is hooked to one of the 4 wires on the spider cluster. The other 3 wires on the spider cluster are hooked to fuel , water temp,and oil pressure guages. 33 is hooked to temp guages 36 to the oil and 28 to the fuel guage. 8 goes to the battery guage and 9 which has juice all the time is not hooked up. 40 is hooked up to the dash lights. 17 to dim and bright light on dash. 85 not hooked up but has juice when ignition switch is turned on. 25,15,11 not hooked up but has no juice at all even when ignition switch is turned on. When I turn the ignition switch on and take a multimeter to the wire connector that plugs into the light switch I have no juice to it. I am missing something but can't figure it out.I have looked at the diagrams but can't find some of the wires I have. Can you give me some information or pictures to show me what I am doing wrong.I also have a 5 wire spider wire cluster that I haven't tried yet. Thanks for any help you give me.

4x4M38 · Post by **4x4M38** » Mon May 28, 2018 8:01 pm

Two questions.

Is your jeep 24 volts?

You say 85 is hot when the switch is on. Is 85 hooked
up to something so it can’t short out when on?
If not, this is dangerous and needs to be fixed
before you go any further.

Shug4 · Post by **Shug4** » Mon May 28, 2018 8:42 pm

It isn't hooked up. Was told it goes to heater switch if one was installed.

mdainsd · Post by **mdainsd** » Mon May 28, 2018 9:49 pm

The lights don't go through the ignition switch. The main feed is from the regulator harness to the circuit breakers. One of the circuit breakers is dedicated to the lights and is "hot" all the time.

Post by **wesk** » Mon May 28, 2018 10:33 pm

Slow down a bit folks. Make sure you read his story completely and take notes.

1- He has an M38A1. NO CIRCUIT BREAKERS except the one inside the main light switch.

2- Yes # 85 if left unused must be insulated with tape or have a dummy connector installed in it.

3 - Shug, you need to tell us the whole story first! As already asked, is your jeep a stock 24 volt system?

4 - That 4 wire switch is a much later manufacture and was not meant for use in the M38/M38A1/M170 series. They are on todays surplus market and fairly cheap so quite a few are being used in our jeeps.

First no juice to light switch at all. I have an ignition switch that has 4 wires coming from it labeled A,B,C and D. A and C are hooked together going to hot wire. Make sure this hot wire is #11 and that it in turn is still connected to #10/#15. If the #10 double connector is not fastened to 15 & 25 then you will not have power to the main light switch, horn switch or the ignition switch. D is hooked to 12 and B has 2 wires coming out from it labeled 85 and 27. 27 is hooked to one of the 4 wires on the spider cluster.

MAKE SURE YOU HAVE THE COMPLETE WIRING DIAGRAM LAYING IN FRONT OF YOU AS YOU WORK THIS PROBLEM.

Shug4 · Post by **Shug4** » Tue May 29, 2018 8:21 am

M38a1 is a stock 24 volt system. I Got the wiring harness from Calvin Ishmael.

Post by **wesk** » Tue May 29, 2018 9:03 am

And have you confirmed continuity from the voltage regulator on Wire #10 to the split connector and then on thru wire # 15 to wire # 11 and the ignition switch and wire 25 to the horn?

Shug4 · Post by **Shug4** » Tue May 29, 2018 7:11 pm

I will take a picture of the wires under dash with the numbers and pit them on here to see. I will be better to explain with pictures. I do have the switch shown above for the m37 on it.

Post by **wesk** » Mon Jun 18, 2018 8:18 pm

Still No Photos?