The creative process uses four steps to solve a problem. They are searching for challenges, identifying the problem, investigating it and finding solutions for the problem. My personal challenge has been with the wiring harness for the glow plug system and starting system on my GM diesel truck. I had to wonder why GM routed the wire harnesses in such a way as to be exposed to the most heat which will eventually destroy the wires and their protective covering.
Since I am in the process of installing a rebuilt engine in the truck I decided to see if I could repair the wiring harnesses and if there was a possible better way to route them. So I could alleviate the electrical problems I have had with this truck specific to this area. I have had other problems with this truck that I have done upgrades on or improvements which turned out very well so I felt confident I could solve and improve on what GM did. The problem is this is on the right hand side of the engine where the exhaust driven turbo charger is located.
The location of the wire harnesses is a couple inches away from the two exhaust pipes and the special oversize exhaust manifold which the turbo mounts too. The heat from all this seems to causes the glow plug wiring system to become inoperative and makes the truck hard to start. This will cause the glow plugs not to operate because the wires feeding them electricity to operate are heat damaged which builds up resistance and low voltage to the glow plugs. Glow plugs need maximum voltage to heat up and aid in cold starting of diesel engines.
Similarly when the wires going to the starter solenoid and solenoid are damaged in the same way the starter won’t operate and the truck will not start. These are some of the problems I have experienced with this truck that I am concentrating on fixing at this time. After studying the situation the factory location routes the wiring harnesses between the cylinder head and the firewall on the cab of the truck. Down to the corner of the block through approximately an inch and half opening underneath a heat shield designed to protect the starter solenoid and the wire harnesses for the glow plugs and the wires connecting to the starter solenoid.
There is a lot of heat from the exhaust pipes and manifold which over time destroys the plastic heat resistant tubing the wires are routed through to protect them and then the wires are exposed to heat and don’t function properly creating the hard start and or no start problems I have experienced with this truck. My ideas to solve these problems are one buy a new wiring harness and install it mounting exactly just as GM did when building the truck. This doesn’t work for me because GM doesn’t make this wiring harness anymore and I find fault with the way it was originally mounted putting in a high heat area causing it to fail.
Another option I thought about would be looking in junk yards / vehicle salvage yards to locate a usable wiring harness. One that does not suffer from the usual heat damage I and others have encountered on these trucks. The problem with this is the wiring harnesses I would find would all have experienced the high heat and be as bad as or worse than the one on my truck. Finding one in good condition would take quite a while and then I would still have the problem of how it is routed which helped cause the premature failure of the wiring harness in the first place.
My next option was to research on the internet through aftermarket auto parts and performance auto parts web sites to see if any one made an aftermarket wire harness for the glow plug system. I found one place that made an aftermarket glow plug wire harness. I felt the price of the wire harness they were selling was to high. After I studied how they designed their wiring harness. I pulled apart the wiring harness GM installed on the truck and studied how the factory made theirs. This led me to a fourth option to make my own wiring harnesses and reroute them. The fourth option is what I decided to do build my own wiring harnesses.
After studying the situation there are two ways to route the wires for the glow plugs. The factory way or run the wires in a new route. I decided I could reroute my wire harness going to the glow plugs. I routed my glow plug wire harness along the top of the engine and around the front of the cylinder head behind the AC compressor which has the wires coming in from the front of the turbo. Since the turbo mounts more to the rear of the manifold I would only have one wire under it and one just in front of the turbo where the most heat is. This is a much better way to route the wires as the factory way had all the wires exposed to the high heat.
Then I could buy some better heat resistant wire insolation to put the wires in which would protect my two most vulnerable wires. When it came to the starter wire I got this idea from my knowledge of the older vehicles wiring systems. I had to study and memorize in automotive technical school I went to in 1983. That was backed up from my years of experience of working on the older ford cars and pickups of the 1960’s and 70’s. Which used a remote starter solenoid mounted high on the fire wall or inner fender by the battery from the factory.
This starter circuit had little or no problems and none from heat since everything was mounted and routed away from the engine and exhaust system. So I adapted it to work on my Chevrolet truck. I rerouted the wire along the fire wall to the inner fender to a remote starter solenoid I mounted on the inner fender. The remote starter solenoid replaced the need of using the one mounted to the starter which is affected by the high heat from the turbo charger and the exhaust pipes. In conclusion I am sure this will solves my starter overheating problem and should last longer than the original design.
I have seen this wiring system work well on other vehicles in the past. I believe my glow plug wiring harness design will work better than the original because it is exposed to less heat than the original design. However I will have to finish installing the engine and drive it for a while to see if I start having glow plug issues again or not. If not then wire harness is more accessible to repair it if it becomes damaged. Looking at it and based on my experience in making and rerouting wiring harnesses in the past. I am confident this will work.