[Motorhome Larry]

Checked plugs,then checked coil wire with grounding quarter in. from block,no spark,except when key was turned it sparked,on/off.Im novice but read somewhere this was indicator,coil not working?I put a new starter in and it turns over fine.Should I take meter readings at ballast resistor,ecu,regulater,coil,dist.I don't have a manual or anything for guide.I would appreciate any advice or data you could share,thanks.

 

[ImperialCrown]

Welcome to Allpar. First, you will probably want a service manual for this. Does this MH have the Dodge B300 front section?
Don't go into this guessing at parts. You will need a wiring diagram and test procedures for diagnostics.
You may find some older Dodge truck wiring diagrams on the internet or at a larger main library. Wiring colors may or may not be the same.
We had a 1978 Honey motorhome with an Econoline E-350 front section.

 

[Adventurer55]

Just a stab in the dark. How about the ballast resistor?

 

[85lebaront2]

First item on MH, check the VIN plate, you may find the chassis is anywhere from 1-2 years older than the actual MH year. The incomplete chassis, either as a cutaway (B300) or if the engine is between the front seats under a removable floor section (larger truck or bus chassis, which will have and Mxxx model, Winnebago Braves were like this). There is no ECU, you have the Chrysler electronic ignition, which will have a small box with a heat sink and a large power transistor on it and a ballast resistor. The ballast resistor can be either a single unit or a dual unit depending on the exact year of the chassis.

I used to hate trying to figure out MHs at my shop, you could have a customer with a 1974 Winnebago, yet when you looked at the VIN, the Dodge M400 chassis was built in 1972. MH manufacturers would buy a block of chassis from Chrysler, then build the "house" on them as the market needed them so the chassis can easily be a year or two old when completed.

 

[AllanC]

. . . .Checked plugs,then checked coil wire with grounding quarter in. from block,no spark,except when key was turned it sparked,on/off.Im novice but read somewhere this was indicator,coil not working?I put a new starter in and it turns over fine.Should I take meter readings at ballast resistor,ecu,regulater,coil,dist. . . ..

You need to determine if you have mechanical breaker points ignition or electronic ignition triggering. Midway through the 1972 model year Chrysler started equipping V8 engines with electronic ignition triggering and all 1973 and later engines received electronic triggering. Remove the distributor cap and look underneath and compare to the images below. And it is possible that the motor home has had an engine replacement after it was originally rebuilt. I am thinking that the engine probably has mechanical breaker points.



Here is a link to wiring diagrams for various model year Chrysler built vehicles.
Mopar wiring diagrams 1966 - 1971: MyMopar - Mopar Forums & Information - Mopar Wiring Diagrams 1966 to 1971 (at http://www.mymopar.com/index.php?pid=27 )

Mopar wiring diagrams 1972 - 1976: Mopar Wiring Diagrams - MyMopar.com - Dodge Plymouth Wiring Diagrams (at http://www.mymopar.com/72to76_wiring.htm )

The attached image shows how to check for voltage levels on the input and output side of the ballast resistor. If you have voltage on the input side of the ballast resistor (ignition ON, not in START) and no voltage on the output side at the ignition coil + terminal, then the ballast resistor has failed. If this is the situation fabricate a jumper wire between the input and output side of the ballast resistor, attach to terminals and then crank engine to see if it starts. If the engine will start then you have found the culprit; failed ignition ballast resistor. If still no start then you will have to investigate the breaker points in the distributor to make sure they are not corroded and opening properly.



This is a Y T video on checking breaker points in a 1960s era Chrysler V8 engine. This is a big block Chrylser V8 but the underlying principles of ignition control are the same.

View: https://www.youtube.com/watch?v=D4MUx5mfVik

 

[dana44]

I agree with determination of your distributor being points or electronic ignition, electronic ignition has two wires coming out of the housing, points has one wire coming out of the housing without having to pull the cap itself. You can do an emergency test of the ballast resistor by running a jumper wire between the two sides and seeing if she will start. If she does, turn her off immediately. Most don't recommend this because it does put too high a voltage to the distributor, but if she starts and you shut her off immediately it won't cause damage and you simply replace the ballast resistor.

 

[chuzz]

Check the bulkhead connector for corrosion too. On one this old, that can quite often be a problem area.

 

[Motorhome Larry]

You need to determine if you have mechanical breaker points ignition or electronic ignition triggering. Midway through the 1972 model year Chrysler started equipping V8 engines with electronic ignition triggering and all 1973 and later engines received electronic triggering. Remove the distributor cap and look underneath and compare to the images below. And it is possible that the motor home has had an engine replacement after it was originally rebuilt. I am thinking that the engine probably has mechanical breaker points.

View attachment 19417 View attachment 19419

Here is a link to wiring diagrams for various model year Chrysler built vehicles.
Mopar wiring diagrams 1966 - 1971: MyMopar - Mopar Forums & Information - Mopar Wiring Diagrams 1966 to 1971 (at http://www.mymopar.com/index.php?pid=27 )

Mopar wiring diagrams 1972 - 1976: Mopar Wiring Diagrams - MyMopar.com - Dodge Plymouth Wiring Diagrams (at http://www.mymopar.com/72to76_wiring.htm )

The attached image shows how to check for voltage levels on the input and output side of the ballast resistor. If you have voltage on the input side of the ballast resistor (ignition ON, not in START) and no voltage on the output side at the ignition coil + terminal, then the ballast resistor has failed. If this is the situation fabricate a jumper wire between the input and output side of the ballast resistor, attach to terminals and then crank engine to see if it starts. If the engine will start then you have found the culprit; failed ignition ballast resistor. If still no start then you will have to investigate the breaker points in the distributor to make sure they are not corroded and opening properly.

View attachment 19421

This is a Y T video on checking breaker points in a 1960s era Chrysler V8 engine. This is a big block Chrylser V8 but the underlying principles of ignition control are the same.

View: https://www.youtube.com/watch?v=D4MUx5mfVik

Checked plugs,then checked coil wire with grounding quarter in. from block,no spark,except when key was turned it sparked,on/off.Im novice but read somewhere this was indicator,coil not working?I put a new starter in and it turns over fine.Should I take meter readings at ballast resistor,ecu,regulater,coil,dist.I don't have a manual or anything for guide.I would appreciate any advice or data you could share,thanks.

Checked plugs,then checked coil wire with grounding quarter in. from block,no spark,except when key was turned it sparked,on/off.Im novice but read somewhere this was indicator,coil not working?I put a new starter in and it turns over fine.Should I take meter readings at ballast resistor,ecu,regulater,coil,dist.I don't have a manual or anything for guide.I would appreciate any advice or data you could share,thanks.

 

[Motorhome Larry]

[URL=http://s345.photobucket.com/user/Mhlarry/media/IMG_20180907_185309_zpsihrlrdnv.jpg.html][/URL]
Here's a shot of my dizzy.I bought new pickup coil,having trouble getting it snug.The only screw is for air gap adjustment,the new coil has one pin preinstalled,the other pin is located on the dizzy,they look the same as the old one.Why can't I get a snug fit?

 

[Motorhome Larry]

Checked plugs,then checked coil wire with grounding quarter in. from block,no spark,except when key was turned it sparked,on/off.Im novice but read somewhere this was indicator,coil not working?I put a new starter in and it turns over fine.Should I take meter readings at ballast resistor,ecu,regulater,coil,dist.I don't have a manual or anything for guide.I would appreciate any advice or data you could share,thanks.

 

[Motorhome Larry]

[URL=http://s345.photobucket.com/user/Mhlarry/media/IMG_20180808_074203_zpsgltdlpjj.jpg.html][/URL]
Awe,so true it is a 72,thankyou.
I hope info can be seen in photo.

 

[AllanC]

. . . . Here's a shot of my dizzy.I bought new pickup coil,having trouble getting it snug.The only screw is for air gap adjustment,the new coil has one pin preinstalled,the other pin is located on the dizzy,they look the same as the old one.Why can't I get a snug fit? . . . .

Here is a clearer image of a Chrysler distributor with electronic triggering. If I have identified correctly the screw that you cannot tighten, try adding some flat washers under the head to take up excessive clearance.

 

[Motorhome Larry]

That is the adjustment screw,I didn't see how it would help,it tightens fine.I must be missing something simple.

 

[AllanC]

. . . .The only screw is for air gap adjustment,the new coil has one pin preinstalled,the other pin is located on the dizzy,they look the same as the old one.Why can't I get a snug fit? . . .

What do you mean by a snug fit? Does the adjustment screw hold the pickup coil from moving? Or you turn the adjustment screw until it will not turn anymore but the pickup coil mounting plate still moves?

 

[Bob Lincoln]

The reluctor gap between tooth and pickup must be set accurately with a *brass* (non-magnetic) feeler gauge to 0.008 inches. If the screw allows this setting to change, that's why it won't start and that must be fixed.

 

[Manic59]

Just a stab in the dark. How about the ballast resistor?

I was going to say the same thing!

 

[Motorhome Larry]

The second question.

 

[Motorhome Larry]

Im going to crawl under there and check out ballast resistor,looks like a dual or 4 poster.Brb with results and photo.

 

[Motorhome Larry]

 

[Motorhome Larry]

Unfortunately I have nothing to report,this is just the kind of luck I sometimes have.I went out to the vehicle thinking,yea this baby be back on the road soon now,armed with my ohm meter and data,wiring diagrams,which by the way all you folks made possible,thank heavens for all you good people,giving good a dvice and shooting info,links,thankyou.
Back to making voltage readings. after making several attempts and not getting any readings I realized I had a serious problem, dead battery and my battery charger I loaned out to a friend so here I sit bummed.