Christopher Stocker

Greetings Again:

To answer recent comments/questions:

* I am finished trying to diagnose this myself. The dealer is now the fifth Porsche specialist, (self imposed), that has spent their time and my money seeking to determine the cause of the cluster failures.

* I am actually hopeful that the problem was caused by the wiring in the fuel level sending unit so that I can stop the burn rate of now close to $5,000 already spent trying to fix this situation, (although I am furious that frayed wiring with a live current in the gas tank is like driving around a bomb).

* The dealer is only diagnosing the issue which causes the cluster to fail. They are forbidden by PNA to identify the specific transistor/component/circuitry in the cluster itself to seek a third party repair. PNA only allows them to sell/program new clusters at $2,500.

* I have attempted to locate a service that can diagnose the transistor/component/circuitry and repair the cluster at a cost of $850, which is higher than simply purchasing a used cluster from a dismantler.

* All other cluster repair services I have spoken with indicate that they are unable to acquire circuitry diagrams from VDO due to PNA restrictions and thus are unable to repair.

* I would very much appreciate any recommended repair services that have the capability of repairing late model Porsche's would be expected.

Thank you.

KrisKringle

Ok, for repairs look for a good aircraft mechanic specialized in avionics.
Your local airport might have a shop or ask around (maybe friend of a friend).

I've seen these guys go through what seems miles and miles of wiring looking for a grounding issue on helos.

Avionics shops charge good money, so if you can offer a guy some extra bucks on his time off, it would be the way to go.
I would bet good money that a capable AME will find your problem.

Good luck!

Christopher Stocker

Greetings Again:

Sorry for my delayed response, however my instrument cluster situation has been resolved.

Diagnosis by dealer of faulty fuel level sending unit was determined to be the cause of the cluster self destructing. Apparently the insulation on the wiring can dissolve over time due to contact with fuel.

So, with a full tank, fuel contacts exposed wiring, causing electrical spike at sending unit. No fuse exists between sending unit and instrument cluster, thus sending unit circuitry receives electrical spike, destroying cluster.

Total cost of multiple hours of shop labor and three replacement instrument clusters ran just over $5,000.

Finally, I sent the failed clusters to BBA Remanufacturing for repair. Unfortunately, none were repairable as company unable to diagnose specific circuitry malfunction and Porsche refused to divulge information.

So, problem solved. Now if I can only find the lone key I had for the car, which is another long and sorry tale, not to mention an expensive, time consuming fix.

Chris Stocker

jimq

a wire with coating thats in a gas tank and disolves when in contact with gas should be reported to the Feds.

redridge

+1

spike = spark

wyovino

Glad to hear that it's been resolved, but sorry to hear about the cost. I hope you have better luck with the key.

fpb111

I would suspect that part of the insulation dissolving problem is the corn based gasohol subsidy. I think the US and maybe Brazil are the only countries that use alcohol infused fuel. I think Brazil uses sugar as a base. I don't know if that would make a difference?

951sickness

Also living in the SF Bay Area with oxygenated fuel....I'm considering changing the sender as a precaution....thoughts?

Pac996

Man what a pain. As far as the exposed wire in the tank I gotta laugh because the metal connectors contacts to pump and sending units sitting in the gas are always soaking in the gas so an extra exposed portion of wire isn;t going to give rise to an outcry. I don't like the arrangement but its the way it goes after many fuel pump repairs. Just doesn;t feel right sticking exposed wires in the tank.

I have a feeling if it was the sending unit it was a case of the wire contacting something other than the fuel or being an intermitent deal where the variations causes spikes trashing the cluster. Or if the fuel pump was replaced a contact wasn't good some place allowing voltage from the pump to enter the readout circuit frying your cluster. A bad ground for the cluster might do that. Where the bad ground was doesn't have to of been in the tank. Notice I didn't say you be getting mislead by the repair guys on what was the cause although......I hope it doesn't pop up again and that they never did any fuel pump or gauge repair before this problem.

pete95zhn

Slightly OT, but I have one extra US instrument cluster, 2002-->, manual, used. $500,-

Macster

I agree the insulation should not be affected by anything in the gas but the fuel tank atmosphere contains an overly rich mixture of gas vapor to air and is not explosive. This is true of our cars -- they have the sender in the tank but also the fuel pump which runs most of the time (but not all of the time, for instance when the tank level is low) submerged in gasoline -- and this is the principle upon which truck/rail car and shipping tankers which carry thousands of gallons to unimaginable numbers of barrels of refined or crude oil rely upon.

The shipping tankers do sometimes explode but it is during the storage tank cleaning operation which does permit outside air to enter/mingle with the residual oil in the tanks that can and does form an explosive mixture. The very act of the cleaning -- using jets of high pressure water -- generates static electricity (like lightning in storm/rain clouds) that sparks the explosion. (Newer tankers use filtered/cooled engine exhaust gases routed to the tank that of course results in a non-flammable mixture because there is not enough oxygen in the exhaust gases to support any combustion.)

Sincerely,

Macster.

Macster

My 02 Boxster has been in the bay area since 04 and has covered approx. 160K miles in that time (total miles is 239K currently and counting) and all on oxgenated (ethanol mainly) gasoline and its sender is just fine. In fact not too long ago (at over 220K miles) the original fuel pump quit and the tech replaced the pump and upon my request inspected the tank and in-tank hardware and found no reason to recommend anything other than the non-functioning fuel pump be replaced. Might add the old fuel pump's wiring, connectors, and fuel hoses looked just fine after all that time in the tank. (Just looked them over -- the pump's in a cardboard box under my office desk.)

Based on my experience, Porsche gas tank level sensor/senders do not appear to be falling prey to gasoline attacking them in numbers to worry about.

Sincerely,

Macster.

Hugh R.

This exact situation has happened with my 2003 996 4s Coupe. I went through the same process - instrument cluster, then another instrument cluster, then pin-testing each pin in the harness, then checking the cluster, then time and money.
I wish I had read this blog earlier. When I took the car in after the second cluster failed, the expert (Mike Callas @ Rennsport in Sealy, TX) said the OBD showed a fault cose for the fuel sending unit. There is a guy in Houston @ Austin Radio who repairs the clusters. We sent the cluster for repair and commenced pin-testing and attempting to diagnose where the short was. Meanwhile we have ordered a new fuel sending unit.

I will tell the forum whether that solved the problem, but I am cautiously optimistic. I just thought you should know that other people have had the exact same problem.

Thanks!

bct1192

Don't mean to revive a dead thread, but...

I have to say thank you. On my way home tonight, the dash lights on my 2003 C2 cabriolet instrument cluster went out. I tried turning the lights off and on to remedy it. The dash lights came on briefly after one of the tries, but immediately went back out. For some reason, when I parked the car they came back on again, but I couldn't help but wonder what kind of costly problem I had on my hands.

I immediately searched rennlist for the problem, and reading this thread I got very concerned that it would be very hard and expensive to figure out. I had basically relegated myself to driving at night without a dash. Then I read the solution, and thought, holy crap, I literally just filled up my gas tank...

Coincidence? I'm not sure, but it makes sense to me to replace the fuel level sending unit and see where that gets me. I'm thinking before my cluster shorts for good (it appears to still be working at the moment).

So thank you for helping me avoid a potential nightmare.

Anyone know the part number for the sending unit? How hard it is to replace? I'd like to do it myself if possible.