Engine does not start, transmission selector problem

Forum for both AC and DC electrical components. From engine alternator to dashboard, inverter to batteries, and everything electrical in-between.
TDJohn
Posts: 552
Joined: Sun Oct 27, 2019 11:34 pm

Re: Engine does not start, transmission selector problem

Post by TDJohn »

Patrick,

Were your batteries fully charged before they were tested by the store???

Discharged batteries will obviously fail a load test, so you could be discarding a good set of batteries that were likely depleted to a charging issue.
John
'95 Serengeti, Cummins C8.3-300
Allison 6spd.
geantbrun
Posts: 48
Joined: Fri Nov 01, 2019 12:52 pm

Re: Engine does not start, transmission selector problem

Post by geantbrun »

I wanted to report about my problem. The guy that sold me batteries yesterday did not verify (me neither!) if the terminals have the good shape. When I removed the caps at the camping, I realized that they have not (new have this big conical shape, mine had a smaller diameter). I’ll have to go the store again to make the change so I’ll know only tomorrow if everything is ok or not.

Meanwhile, a neighbour at the camping (that happens to be an electrician) told me that he doubts the problem is linked to the batteries. After all, the engine started the first morning we began our trip and two hours of road later, the batteries should have been fully charged if the alternator had functioned properly. When I told him that the automotive guy tested the batteries and declared them dead, he was not convinced (after all, as he said, they also sold me batteries with the wrong terminal type!).

So when I’ll go tomorrow, I will try to get my old batteries back, fully charge them (the electrician has a charger) and make a test to have a measure of voltage when engine running (as Brett and John asked at first). I will also check that comes from the isolator is connected to the good terminal (John, do I have an isolator for sure?)

Question: I know I anticipate a little bit but supposing the alternator is wiped out, does it have to be replaced or can it be repaired (in general) ? I ask the question because depending of the answer, I will ask the tower to go to the garage for a repair or to my brother’s home in the country where we can wait for the new part and possibly make the replacement by ourselves (my garage is too small to keep a motorhome more than two days).

As usual, your comments and help are invaluable,
Regards
Patrick
geantbrun
Posts: 48
Joined: Fri Nov 01, 2019 12:52 pm

Re: Engine does not start, transmission selector problem

Post by geantbrun »

John, sorry I didn't see your last message (don't have wifi at the camping, so it's a little bit complicated for me to follow the discussion). No, they didn't fully charge the batteries at the store. The guy took a measure (I don't know which one) that was apparently sufficient for him to say it would serve nothing to charge the batteries.

By the way, even I did not disconnect the batteries recently, I also check for the battery isolator. I didn't find one (I looked for something like this: https://youtu.be/g30jUUWUl74?t=135). I saw a wire that is wrapped in a red plastic coat and that was connected on the negative terminal of the battery in the back though. Picture included.

Patrick
Safari Sahara '96
Allison transmission 6sp
Attachments
IMG_5931.JPG
IMG_5931.JPG (2.43 MiB) Viewed 7575 times
geantbrun
Posts: 48
Joined: Fri Nov 01, 2019 12:52 pm

Re: Engine does not start, transmission selector problem

Post by geantbrun »

And following question: does anyone know the type of alternator I must be looking for, should it be the problem. I will start searching today, just to be ready when the deed is done.
Patrick
Safari Sahara '96
TDJohn
Posts: 552
Joined: Sun Oct 27, 2019 11:34 pm

Re: Engine does not start, transmission selector problem

Post by TDJohn »

Patrick,

This is the way underhanded and/or ignorant battery shops sell batteries. They know you will be moving down the road to the next town, so they test a flat battery, and naturally it will flunk, and bingo, another two batteries sold.

You isolator should be located inside your engine compartment, bolted to the front passenger side of the bed box. If it is original, it is blue in color.

Here is a link of what it would approximately look like: https://www.waytekwire.com/item/80051/E ... Isolator-/

Before you start changing parts, I would strongly suggest that you trace the wires coming from the isolator (assuming you have one, it might have been upgraded to a solenoid type of isolator, but I doubt it). The wire connected to the center post should go to the alternator, the other two side posts should go to the battery positive post of each battery bank. Usually the wire connected to the left/drivers side post goes to the engine battery bank, and that is the wire that often gets mixed up and incorrectly gets connected to the battery negative post, because the wire is black in color.

If your alternator is bad, you can choose to have it rebuilt or a new one installed. New, not rebuilt, Leece Neville and AC Delco are both very good alternators, and should serve you a very long time. The replacement that you do get must have the remote sense wire option. This is where the shops often botch it up. They take the easy route and eliminate the remote sense wire, which is needed because of the 0.7 voltage drop that occurs in the isolator. It may not seem like much, but if that voltage drop is not compensated for, your batteries will not properly charge, and won't top off.

Check your PM box, I sent you a PM.
John
'95 Serengeti, Cummins C8.3-300
Allison 6spd.
stuplich@ymail.com
Posts: 1146
Joined: Mon Oct 28, 2019 8:51 am

Re: Engine does not start, transmission selector problem

Post by stuplich@ymail.com »

geantbrun wrote: Wed Jul 29, 2020 10:13 am And following question: does anyone know the type of alternator I must be looking for, should it be the problem. I will start searching today, just to be ready when the deed is done.
Patrick
Safari Sahara '96
Patrick
To avoid compatibility issues it's best to have your alternator rebuilt...(to find a alternator rebuilder Goggle "alternator shop near me", or ask at any auto parts store or truck repair shop).

BTW originally your '96 Sahara would have had a solid state, diode based, battery isolator....
similar in appearance to this:
Image
Mel
'96 Sahara 3530, mine since '01
250 hp 3126 Cat, MD3060 Allison
geantbrun
Posts: 48
Joined: Fri Nov 01, 2019 12:52 pm

Re: Engine does not start, transmission selector problem

Post by geantbrun »

Progress report: I went to to the store to return their batteries they tried to sell me and get back mine after full charge. Voltage reading: 12.2. I started the engine. Two minutes later, the reading was 12.05, so it seems the alternator is the problem. There was also the possibility of a problem with the isolator. I could not see where the small wire that comes out of the pole of the isolator goes into (I checked the two poles, right and left). Is there another thing I can do to test the alternator or the isolator? (BTW I also checked the two alternator straps, they seem tight).

Questions: can I go back home with an alternator that is wiped out? (110 miles away). When I did the trip the other way three days ago, I could not restart the engine after 50 miles (after shutting off at gas station). After the boosting, I could reach the camping but 5 or 10 miles before the arrival, I had problems with the Allison ECU. At the camping, I had no possibility to shift anymore (no neutral, no reverse). So is it safe to try to go back home in the city (reverse needed to enter my driveway!) or is it safer to go to my brother's home in the country (no reverse needed). Out of curiosity, when on the road, what is draining the chassis batteries except the Allison ECU ? And another thing, do I put the transmission at risk on the road if the ECU is no more available and I still drive?

If I have to replace the alternator, Mel's opinion is to rebuild instead of replace (for compatibility reasons). Does this line of reasoning apply even if I make sure the new alternator have the remote sense option? I ask the question because it's probably faster/easier to go with the replacement option (maybe I'm wrong).

Thank you again for your supporting help!
Patrick
Safari Sahara '96
CAT 3690
Allison 6sp
wolfe10
Posts: 222
Joined: Sun Oct 27, 2019 4:12 pm

Re: Engine does not start, transmission selector problem

Post by wolfe10 »

If you have a digital voltmeter, this is EASY to diagnose.

First, verify that all wires, Including sense wire are clean and tight. If that small wire from the Sense terminal of the alternator does not read exactly the same voltage as the chassis battery, just replace it (connect to any place that has chassis battery voltage-- the battery isolator is a good place.

Then with the engine running at around 1,100 RPM, go to the battery isolator.

Center lug from alternator B+ should read in the mid 14's.

Each outer lug (one to chassis battery, the other to house battery) should read about .7 VDC less.

Let us know what you find.
Brett and Dianne Wolfe
Ex: 2003 Alpine 38'. Ex 1997 Safari Sahara. Ex 1993 Foretravel U240
Moderator, FMCA Forums 2009-2020
Chairman, FMCA Technical Advisory Committee 2011- 2020
Moderator, http://www.dieselrvclub.org/ (FMCA chapter) 2002-
geantbrun
Posts: 48
Joined: Fri Nov 01, 2019 12:52 pm

Re: Engine does not start, transmission selector problem

Post by geantbrun »

Thank you Brett for your answer. Sorry for that but I have to ask you some very basic questions, don't forget that I'm a beginner... but I want to learn!

About the sense wire, I cannot see it. The alternator seems very well hidden. Is there someone who knows enough my specific model (Mr Mel maybe?) to tell me from where I should see this wire (bed? under coach?). Suppose I can test it and conclude that it must be replaced, do you tell me Brett that I can connect one end of the wire to the CENTER terminal of the battery isolator (as opposed to left or right)?

About the testing of the battery isolator itself at 1100RPM, when you say "Center lug from alternator B+ should read in the mid 14's.". Could you explain me with more details what I should do? Positive wire of my digital voltmeter on center lug of battery isolator and negative on the ground (any steel rod?) ?

I will do the test tomorrow as there is a thunderstorm here in the moment...

Thank you again!
Patrick
Safari Sahara '96
Allison 6sp
TDJohn
Posts: 552
Joined: Sun Oct 27, 2019 11:34 pm

Re: Engine does not start, transmission selector problem

Post by TDJohn »

geantbrun wrote: Thu Jul 30, 2020 11:47 am Progress report: I went to to the store to return their batteries they tried to sell me and get back mine after full charge. Voltage reading: 12.2. I started the engine. Two minutes later, the reading was 12.05, so it seems the alternator is the problem. There was also the possibility of a problem with the isolator. I could not see where the small wire that comes out of the pole of the isolator goes into (I checked the two poles, right and left). Is there another thing I can do to test the alternator or the isolator? (BTW I also checked the two alternator straps, they seem tight).

Questions: can I go back home with an alternator that is wiped out? (110 miles away). When I did the trip the other way three days ago, I could not restart the engine after 50 miles (after shutting off at gas station). After the boosting, I could reach the camping but 5 or 10 miles before the arrival, I had problems with the Allison ECU. At the camping, I had no possibility to shift anymore (no neutral, no reverse). So is it safe to try to go back home in the city (reverse needed to enter my driveway!) or is it safer to go to my brother's home in the country (no reverse needed). Out of curiosity, when on the road, what is draining the chassis batteries except the Allison ECU ? And another thing, do I put the transmission at risk on the road if the ECU is no more available and I still drive?

If I have to replace the alternator, Mel's opinion is to rebuild instead of replace (for compatibility reasons). Does this line of reasoning apply even if I make sure the new alternator have the remote sense option? I ask the question because it's probably faster/easier to go with the replacement option (maybe I'm wrong).


Thank you again for your supporting help!
Patrick
Safari Sahara '96
CAT 3690
Allison 6sp
Patrick,

Did you receive my private message? Please check your private message inbox (click on private messages in the top right hand corner of the page).

You state that your batteries were fully charged, showing 12.2 volts. Just so you are aware, that is not fully charged, at 12.2v, the battery is 40 to 50% discharged. I would suggest to keep the battery charger on them much longer.

Also, since you're new at this, there seems to be a bit of a communication gap of describing what you are seeing and checking. Pictures of what wires you are checking and talking about would be helpful. Please take pictures from a bit of a distance, so we can see the surrounding area, this helps us see what is going on and help us orient ourselves to your setup and situation.

Please do as Brett said, and yes, connect the meter as you stated in your question to Brett. I will let Brett answer the rest of the questions you have for him, to not create extra confusion.

As for the small sense wire hooked up to the isolator, if that wire has an inline fuse, be sure to check that fuse to make sure it is not blown.
Besides one small wire connected to the isolator, there should be three thicker gauge wires (approximately 6 or 4 gauge size), please trace the two outer thick wires that are connected to the right and left side studs of the isolator. Both of those thicker wires should trace down and be connected to the positive of each battery bank, meaning, one wire goes to the house bank and one goes to the chassis battery bank. As you are tracing these wires, they might connect to the boost solenoid, continue tracing them past the solenoid. If you have questions, please post pictures of what is in question.

Back to your second to last post, as quoted above.
To try to answer your question regarding if you can drive your coach with a non charging alternator. You can if you do a simple temporary modification AND provided that you have a functioning generator that you will need to run while your driving.
If you do have a functioning alternator, right before departure, connect the two heavier gauge wires, that are connected to the outer posts of your isolator, connect them together. Meaning move the wire from the left stud and connect it to the right stud, or vice versa, move the wire from the right stud and connect it to the left, (doing this simple procedure ties both battery banks together). You then start the generator. The generator will provide power to the inverter/charger, allowing the it to start charging the batteries. Normally running the generator would only charge the house battery bank, but being that you now combined both battery banks, it will also now charge you chassis batteries. This will allow you to drive home, (assuming you have enough fuel to run your generator for the entire trip).

As for your question on what draws on the chassis battery bank while the engine is running and while driving, it is various items like; CAT engine ECM, wiper, heater motor, headlights, brake lights, cruise control, vacuum pump, air compressor for Pac Brake, etc.
John
'95 Serengeti, Cummins C8.3-300
Allison 6spd.
Post Reply