why does fuse 23, transmission, 10 amp, keep blowing and leaving me stuck in 3rd gear? 2008 Equinox

Fuzzyyyy

Chevy Equinox, 2008. Hard to take off in 3rd.

thecardoc3

You didn't specify which engine/trans combination, (3.4l Vin F?) but I might have found the correct system schematic anyway. Looking at the schematic this fuse delivers power to the transmission control module on pin 11 (pink) and is labeled the ignition input. The transmission control module outputs this power to all eight shift control solenoids. It's noteable that it also controls the ground circuit for three of those. Wiring damage either internal or external of the transmission could be in play. A solenoid issue cannot be totally ruled out without testing which would be done by commanding the solenoids on/off and measuring how much current is flowing. If I was going to take this in and analyze the issue I would start by asking some questions about when and how often the fuse fails. Those first questions would be:

Does the fuse fail immediately or does it last for a while? If it lasts for a while how long in time/mileage?

When the fuse fails, does it seem to happen when the vehicle is in one particular gear or a combination of gears?

What about how fast is the car going when it happens?

Is there anything else that you can think of that would amount to a pattern or set of circumstances where the fuse is likely to fail? aka Hard acceleration? Light acceleration? Turns? Braking?

One thing a tech should not do is just open the transmission up and just look for a possible sign of trouble. The current is going too high when the fuse fails protecting the system. This can be measured and from there the individual circuit that has the problem identified and then ultimately the exact location can be proven and dealt with.

Fuzzyyyy

I understand the procedure, just don't have the tools. was sonar tech in Navy and studied electronics. Makes perfect sense and is detailed enough to make it seem easy. I couldn't have figured it out but I can follow the explanation.

PF_Flyer

Could be a problem with shift solenoids in the transmission. Something fried internally that is causing the fuse to blow. Getting any codes on a scanner?

Fuzzyyyy

fuse f ails soon as put into drive. Used to last awhile. If let set for a few weeks, it lasts about 15-20 miles. vin is 2CDNL13F486047903. Ron Craft Chevy Baytown Tx. says only one shift solenoid, to the right of the floor shifter under the shift cover, but that doesn't sound right. They want $150.00 to check codes and am retired and limited income and cannot afford that. Need help as I don't want to burn up clutch. Runs great in reverse and in drive after it gets up to speed. Other than that I love the Equinox, which I hear is not all that common.

thecardoc3

Sounds like you talked to a service advisor who is thinking about a failure with the shifter interlock solenoid that is a fairly common issue. But you aren't having a problem with the shifter (fuse "RVC" in the under hood fuse block) as much as you are having an issue with the transmission shifting. I always hated when a service advisor failed to understand and then relay the correct information regarding a problem with a given vehicle. It didn't always result in the techs failing to get the repair right anyway, but it made it take longer to get onto the correct track.

Fuzzyyyy

Long explanation: Bought it used and worked fine. After about 100 miles the 10 amp fuse, #23 transmission, blew. Replaced and it ran great for another 100 miles approx. Sitting in driveway I replaced the fuse but forgot to turn off ignition and sparks jumped from fuse juncture to fuse and of course blew the fuse. Local mechanic drove it up and down the freeway 25 miles each way and no malfunction. Picked up and tried to drive home and got 4 miles and fuse blew and stuck in 3rd. Took it back. He said he didn't do anything to it but it ran good. My son went and drove with him up and down the freeway and ran great. Picked it up and same problem, same distance. Told them both city streets bumpy and freeway smooth! Mech kept for 3 months while worked on other cars and did research. Called me and said worked fine and he did nothing to it. He drove it the 10 miles to my house and dropped it off and it ran fine. My son took him home in his truck. I drove it about 20 miles and again fuse blew and again stuck in 3rd. I always thought it was s short in the wiring but I'm not a mechanic. Hope this is some help.

thecardoc3

It is quite likely that there is damage to the harness that randomly momentarily goes to ground. I can explain how I would track this down, you are going to need an electronics specialist to use this routine.

I would pull the fuse and install a "fuse buddy". This separates the fuse from the fuse block and allows me to put a low amps current probe on one of the wires and measure the current flowing in the circuit to the module on my PICOSCOPE. Then I am going to take three more probes and connect them to the various output wires from the module to the transmission. The wires would be grouped through the various probes so that depending on which probe(s) I see the current spiking I would be able to figure out exaclty which circuit has the failure.

For example there are eight solenoids that get power. I would number the circuits on the schematic 1-8.

Now for the current probes. Channels A, B, C, and D, on the scope.
Channel A will be the fuse buddy.
Channel B circuits 1,4,6,7
Channel C circuits 2,4,5,8
Channel D circuits 3,5,6,

Channels 7 and 8 would have the wires pulled loose enough from the harness to route them through the current probes in the opposite direction. That way they make a spike going downward when current flows in them.

If you look at that logic table a short ocurring on wire number 4 would give me spikes on channels A, B and C.

Now all I need to do is drive the car and monitor how much current is flowing in each circuit. The fuse doesn't even have to blow because I will be looking for spikes in the current that exceed the fuses rating but for too short of a time to cause it to fail. Once I know exactly which circuit is affected, then I can modify this and place probes at different sections of that circuit and narrow down the location.

thecardoc3

Fuzzyyyy said:

I understand the procedure, just don't have the tools. was sonar tech in Navy and studied electronics. Makes perfect sense and is detailed enough to make it seem easy. I couldn't have figured it out but I can follow the explanation.

That's something I came up with a number of years back when I had to figure out a false shift command problem, and have modified it as required for different concerns. I shared that on some professional technicians forums and have gotten to see it be re-shared many times since then. It has served other techs well when having to analyze a problem like this. Nobody ever taught anyone how to test like that, we had to create this and other advanced routines like it ourselves.