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Letter 43

Isuzu Trek Members Infoletter #43
July 2020

Welcome to the Isuzu Trek Infoletter #43.

The I-Trek infoletter mailing list is now managed in a Google Group:!forum/i-trekinfoletter. If you would like to be included in this exclusively Isuzu Trek group please request inclusion or e-mail the editor Bret Medbury for info at isuzutrek (at) or islandduo (at)


  • Awesome Honey Hole of Info, Northwest Trek Fun Club and Mary Carlson
  • Put your Generator on Slides, Clark Van Galder
  • Holding Tank Repair, Greg
  • 91-93 Heart Inverter 101, Sulaiman Kahn  
  • 91-93 AC Electric Distribution Diagram, Richard Kreutzer
  • Generac Starter Replacement, Bret Medbury
  • Cooling System Part Numbers, Bret Medbury and Greg

Awesome Honey Hole of Info    Thanks to Mary Carlson and the Northwest Trek Fun Club 

Did you know there is a cache of Isuzu specific information which the Northwest Trek Fun Club has graciously provided us space to store on their website at Also you will find all the history and previous issues of this InfoLetter and other information there as well, just use the drop down under the Infoletter tab.  Also if you have or know of information that you feel would be an asset to this collection of information please inform myself at islandduo(at) or Mary Carlson at hmcarlson30(at) 

Put your Generator on Slides  Thanks to Clark Van Galder  clarkrvg(at)

Drop the generator with its frame work and disconnect elec and lp. Cut a bigger door to accommodate the slides, hinging on the right side, (left side maybe better)welded  reinforcement for better support underneath to the steel frame. I left the original door intact so it opens with the bigger door.

The generator sits in a bolt up frame. Cut the frame in half horizontally and welded slides on both top and bottom half of the frame work on each side. Then extended the lp and electric about 14 inches. Use heavy duty locking slides with no plastic.

Easy to tune and cool and remove if need be…

Editor’s note: Clark did this on his 94 which has a Onan generator, however with a little innovation the same idea would work on the earlier Isuzus having the Generac generator.

Holding Tank Repair   Thanks to Greg     grrreaat(at)

(Click the link below to open the pdf file on the article)

Spin Weld Tank Repair (w-pics)

91-93 Heart Inverter 101    Thanks To Sulaiman Khan   sulaik(at)\

How External Control of Heart Interface Inverter Works

The purpose of this info is to help understand and aid in troubleshooting the control of the inverter in a 1993 Safari Trek. My Trek, I believe still has the original inverter, a Heart Interface Inverter model number HF-12-1200U (Other sticker on unit — Model 80-1201-12, S/N 57639, Date 02/93).

There are THREE switches that will turn the inverter on. ALL three must be off to turn it off.

The first is on the inverter itself, this switch should ALWAYS be in the off position. This switch is a direct control of the inverter internally.

The second is on the dash and it is for the backup camera. In the original configuration, the original TV was the monitor for the backup camera which required 120 volts to operate, so when you turned on the camera it simultaneously activated the inverter. Most likely this function can be eliminated today as most Treks have been converted to stand alone 12 volt powered monitors. My Trek has a light weight LCD TV which requires the 120 volts, so mine still has the original wiring configuration.

The third is in the galley corner and it should be the primary control of the inverter.

The second and third way of control as described above are external control of the inverter via the 9 Pin plug on the inverter.  On the 9 Pin plug cable connector, Pin 3 is connected to a red wire and less than a foot away in the loom to a pair of green wires and Pin 4 is connected to an orange wire and less than a foot away in the loom to two black wires. A pair of green and black wires run to the galley corner and a pair of green and black run to a relay on the driver’s side under the hood. This relay is on the right wall and mounted upside down.

Pin 4 at the 9 Pin plug on the inverter always has 12 volts present regardless of the position of the switch on the inverter. Since pin 4 is connected to the black wires the black wires should always have 12 volts present. When the 12 volts is applied to Pin 3 (green wire) the inverter will turn on. So, the galley switch connects the black to the green wire to turn on the inverter as does the relay under the hood when the coil is powered by the red wire from the camera switch.  The White wire on the relay is a ground.  Red and white operate the relay coil and the green and black go to the contacts.

Special thanks to Bret and Richard Kreutzer in helping me trying to figure out why I could not control my inverter externally. The above description is a summary of back and forth emails until the problem was found on my Trek. The issue I had was that I could not turn on the inverter from the galley or the camera switch. The problem was no 12 volts on pin 4 which ends up on the black wire. No 12 volts on pin 4 is an indication that the problem was internal to the inverter. In my case there was a blown 2 Amp fuse on the control board. See 3 photos below:

2 Amp Fuse


Internals of Inverter, Control board on the right with 2 Amp fuse


Control board close up view of 2 Amp fuse


Editor’s note: This relay is frequently the cause of trouble because the upside down mounting allows it to collect water and malfunction.

91-93  AC Electric Distribution Diagram  Thanks to Richard Kreutzer     rgkreutzer(at) 

Editor’s Note: The 120 volt AC electric distribution in a 91-93 Isuzu Trek is different than later Treks. The 91-93 Treks have a separate stand alone inverter not a combination inverter/charger with internal transfer switch (Freedom 10) like the later Treks. Richard has kindly modified a 94 circuit diagram to better show that difference. Be aware that some Treks include the outside patio and/or bar outlets on the inverter circuit.


Generac Starter Replacement     Thanks To Bret Medbury  islandduo(at)

One of the glass slippers of the Generac NP52G generator is the starter Bendix gear. Failure of the starter drive Bendix gear seems relatively common and it is not easily replaced, especially on the road.

The engine that drives your Generac is a garden variety Briggs and Statton Lawn tractor engine and therefore so is the starter. A replacement starter or starter Bendix drive is much better purchased from your local small engine repair guy or on line. There are two commonly used Bendix drives, the one in the photos here seems to be the less failure prone, the other having a cross rollpin I would change out. Here are the two –  

309C is my choice.

The Briggs and Stratton engine Model etc. are on a tag at the very base of the engine crankcase visible through the generator access door. My engine is:

Model 303775,  Type 0119-01,  Code 92041011

Well I had what I believed to be the more durable starter Bendix drive, but it failed anyway, see photos. The part numbers to replace the complete starter are Briggs P/N 499521 or 795121.

I chose to drop the Genny as trying to get to it with the genny installed is very difficult. I do not raise a lot as I do not need to extract it, just drop it and work through the door. I have included some photos that hopefully will reduce the anxiety for anyone choosing to do this repair.  I did this alone, but an extra pair of hands would be welcome. The genny will balance pretty well on a single floor jack as long as you have one hand to steady it and a good rolling surface. Remove the exhaust system and disconnect necessary cabling and propane supply hose.

Note: I was able to leave the large 120V line leading out of the genny connected and it might have been possible to leave the 12 volt cable to the starter solenoid except I had another lead there that did have to come off regardless so it got disconnected and insulated to within an inch of it’s life… 

BE AWARE there is a ground cable from the very back of the genny base plate to the frame and it is short. Support the genny with the jack and remove the four mounting bolts located along each side of the base mount rails and slowly lower the genny. Do not remove it from the jack, it is hard to get back on. Remove the top screen and the black cover from the right side so you can remove the large black cover, then the sheet metal cover from the left rear revealing the starter. Now you can remove the starter and either replace the Bendix or the entire starter depending.

I would not advise replacing just the gear as, according to my highly trusted local Briggs repair guy, a worn nylon helical is what caused my gear to break. I had replaced just the gear two years ago as “preventative” maintenance. There is a kit including all the Bendix parts which is what I should have done, it is on there now.

Re-assembly is the reverse. It takes a bit of jockeying to get the mount bolts to align with their mounting slots, but when you get one in get a nut on it, then go for the second, etc.


Cooling System Part Numbers ETC.    Thanks To Bret Medbury and Greg

Have you ever wanted to replace all the rubber hoses in the cooling system? Below are the part numbers and some discussion.

The upper radiator hose is 8-94455-065-1 
(The 8 digit number (GM) sometimes found when searching is always the middle 8 digits, in this case 94455065 the same will be true for the others.)

Lower hose 8-97032-227-1
Water bypass hose   8-94132-490-0
Turbo feed hose   8-97106-968-0
Turbo return hose  8-94338-876-2

I believe turbo hoses can be done from bulk cooling hose at the parts store. I replaced all original clamps with worm style clamps as I had to cut some of the originals to remove them.

Greg found Brand name aftermarket part numbers for the above saving major $$

DAYCO #70081 ‘radiator upper’ $9.33
AC Delco #14231S ‘bypass hose’  $9.77
AC Delco #26238X ‘radiator lower’ $34.79 ( This one is HUGE)
AC Delco #20012S also ‘radiator lower’ $9.33

For most all of the work you’ll be laying across the top of the motor.  1- Use a piece of wood or very stiff box to protect your oil dipstick from leaning on it.  It’s more fragile than you’d think!  2- If you’re re-using the original hose clamps, I did and they’re a pretty good design for this app, they have these little PITA washers that can and WILL slip out while loosened.  I used a sheet of HD aluminum foil to line a little catch pan beneath each place I was working.
The Turbo Hose(s) you’ll have to get from Isuzu but be ready for some confusion with the part numbers.

FYI Stuff

Officially I have retired from providing LEDs to inexpensively convert your Trek to LED interior lighting. HOWEVER I am always willing to accommodate and Isuzu Trek owner. Selection will be a bit limited, but still very adequate and of course the price and service just can’t be beat.  In addition, by popular demand, I also have an assortment of fuses that light up when they blow. These things can save you minutes or hours of searching for that blown fuse.

I have paper copies of the original Owner’s manual to which I have added a factory price sheet (see what your Trek cost new, you will be surprised) plus a disc containing complete parts list for your Chassis and another disc including the complete shop manual for your chassis. The parts list provided to us by Denney Jones is especially useful because it makes finding parts a whole lot easier once you have a part number and this list includes everything right down to the tiniest screw.

Anyone interested in any of the above treasures please contact me directly at islandduo(at)

Notice:  No one knows what the future holds relative to the current Pandemic, but at this time we still plan to have a Trek Gathering in Quartzsite Az beginning January 14, 2021. Duration and other details are still being planned, however circle that date now so you do not miss out. If you have never joined us at Quartzsite check it out, it is free no host dry camping in the desert, over 50 Treks typically attend. Last year we had 12 Isuzus included in that group. E-mail me at islandduo (at) and I will fill you in with details.

Recall Corner:  Be aware Harbor Freight has issued a safety recall for at least two styles of jack stands  and     Also be aware that many Jack stands sold by HF are rated by the pair Vs singly as is the industry standard. So if you own HF jack stands rated at 3 tons check carefully that the rating does not mean 3 tons when used as a pair or 1.5 tons EACH. We do not want any accidents out there.  

Update as of 7/10/2020:  Now they have recalled one of the jack stands used as a replacement for the previously recalled stands.