Canadian Hummer Club Forums

Hi gents!

Hope everyone has been doing well and getting their trucks ready for the summer. I just scored a new set of tires and wheels (17" Aluminum rim) from a gent that took them off the day he bough his H1. I'll post some pictures once the weather clears up.

So my 1995 had been having some electrical issues. At random it would go into limp mode, stuck in second gear. This doesn't happen all the time just randomly. I have checked the TPS, speed sensors and have found no discrepancies. I came across an article on Flashoffroad.com that describes my issues. Towards the end of the write up the guy says it was just a plug at the firewall. Can someone help me out and tell me where that plug is? Here is the link and below is what it says in the article: http://flashoffroad.com/electrical/elec ... oblems.htm



"My 95 Won't Go Out of Limp Home Mode

Here is what I have replaced so far in an effort to correct the problem on my 95. The TPS (throttle position sensor), the input speed sensor (transmission), the output speed sensor (transfer case), rebuilt the connector plugs at the ECM, and then both the A and B solenoid in the transmission. The code on the scanner returns a bad B solenoid but replacing it did not fix the problem.



After all of this we replaced the ignition switch. The early hummers had a computer for the transmission, not one for the engine. If your truck is running you theoretically can disconnect the batteries because it is a diesel and doesn't need an electrical spark for ignition it will continue to run. Once you do this you will have lost power to the transmission PCM (power control module). The trans will now go into limp mode.If you disconnect the battery on a running Hummer Diesel engine you will ruin the alternator. It is a characteristic of the alternator.



In other words a possible malfunction in the ignition switch may cause power loss to the trans PCM. A loose switch could lose contact when you hit a bump our just because it's worn.



My Hummer kept jumping into limp mode (stuck in second gear). That is the problem which caused me to bring to two different shops and then the dealer. When I first started to check everything myself, I checked the plug at the trans, the connecter going through the floor near the dog house, and of course changed both solenoids, the input speed sensor, the output speed sensor (on the transfer case tail shaft), and the throttle position sensor. Nothing fixed the problem until AMG told the dealer to check the plug at the firewall. That fixed it. I myself have never seen this plug although I have been all over the vehicle. I even rebuilt the plugs that go into the TCM (harness was unavailable and I knew I could put new plugs on).



AAMCO just replaced all of the solenoids in my tranny for $400.00. I was in limp home mode and feared I needed a whole new tranny."



Thanks for any help!

Pavel

1995 H1 6.5 NA

[quote name='logicbyondreason' timestamp='1336092955' post='36607']

Hi gents!

Hope everyone has been doing well and getting their trucks ready for the summer. I just scored a new set of tires and wheels (17" Aluminum rim) from a gent that took them off the day he bough his H1. I'll post some pictures once the weather clears up.

So my 1995 had been having some electrical issues. At random it would go into limp mode, stuck in second gear. This doesn't happen all the time just randomly. I have checked the TPS, speed sensors and have found no discrepancies. I came across an article on Flashoffroad.com that describes my issues. Towards the end of the write up the guy says it was just a plug at the firewall. Can someone help me out and tell me where that plug is? Here is the link and below is what it says in the article: http://flashoffroad.com/electrical/elec ... oblems.htm



"My 95 Won't Go Out of Limp Home Mode

Here is what I have replaced so far in an effort to correct the problem on my 95. The TPS (throttle position sensor), the input speed sensor (transmission), the output speed sensor (transfer case), rebuilt the connector plugs at the ECM, and then both the A and B solenoid in the transmission. The code on the scanner returns a bad B solenoid but replacing it did not fix the problem.



After all of this we replaced the ignition switch. The early hummers had a computer for the transmission, not one for the engine. If your truck is running you theoretically can disconnect the batteries because it is a diesel and doesn't need an electrical spark for ignition it will continue to run. Once you do this you will have lost power to the transmission PCM (power control module). The trans will now go into limp mode.If you disconnect the battery on a running Hummer Diesel engine you will ruin the alternator. It is a characteristic of the alternator.



In other words a possible malfunction in the ignition switch may cause power loss to the trans PCM. A loose switch could lose contact when you hit a bump our just because it's worn.



My Hummer kept jumping into limp mode (stuck in second gear). That is the problem which caused me to bring to two different shops and then the dealer. When I first started to check everything myself, I checked the plug at the trans, the connecter going through the floor near the dog house, and of course changed both solenoids, the input speed sensor, the output speed sensor (on the transfer case tail shaft), and the throttle position sensor. Nothing fixed the problem until AMG told the dealer to check the plug at the firewall. That fixed it. I myself have never seen this plug although I have been all over the vehicle. I even rebuilt the plugs that go into the TCM (harness was unavailable and I knew I could put new plugs on).



AAMCO just replaced all of the solenoids in my tranny for $400.00. I was in limp home mode and feared I needed a whole new tranny."



Thanks for any help!

Pavel

1995 H1 6.5 NA

[/quote]



What codes were showing? The 700 series codes descibe electical and /or performance related faults. For example the B solinoid could give a P0756 code which is performance related ie stuck valve, leaky solenoid or give you a P0758 which is electrical and indicates a poor conection in the ground or hot wires. Post the codes!!!

I have a sneaking suspicion its the valve body and a stuck valve either the 2-3 or the 3-4 shift valve. If the code was a P0756 thats my bet.

[quote name='GreenMeanie' timestamp='1336175819' post='36619']

What codes were showing? The 700 series codes descibe electical and /or performance related faults. For example the B solinoid could give a P0756 code which is performance related ie stuck valve, leaky solenoid or give you a P0758 which is electrical and indicates a poor conection in the ground or hot wires. Post the codes!!!

I have a sneaking suspicion its the valve body and a stuck valve either the 2-3 or the 3-4 shift valve. If the code was a P0756 thats my bet.

[/quote]

DUBBLE CHEAK THE TPS THEY NEED TO BE SET UP WITH A SCAN TOOL .6 VOLTS AT THRODLE REST

AGIAN WHAT CODES

I BELIVE ITS OBD 1 WITH ARE TWO DIGIT CODES

WHERE ARE YOU FROM.

i had the same sort of issue with my 4l80e turned out to be the rear speed sensor on transfer case new one came with a shim as well weird one couldnt even find a cross reference for it got it from dave hummer parts guy mine acted intermitately have you removed yours and cleaned it at all or see if tone ring niked it at all another thing to give it away is your speedo will act up as well just a thougth its a cheap fix