[TestPoint]

I have been invited to assist my grandson diagnose the transmission reverse issue with his newly purchased '02 (140k miles). The previous owner was having reverse problems to the point that he decided to sell an otherwise excellent car. He was the first owner and never had the ATF changed. He had the ATF changed as a result of the issue but that did nothing to affect the failing reverse. It worked fine when first driven, no slipping, acted normal. Shortly it began to fail to engage and now does not engage at all. It is not in reverse and just slipping.

He did buy at a price assuming replacing the trans so we are not real disappointed.

I am familiar with the ZF transmissions of that era and have full documentation on them. I know that the shift lever is a switch operating a solenoid on the bottom of the transmission under control of the Trans Control Module.

What is the probability of repair short of replacing the trans?

No CEL codes but understand that my reader will not read trans codes

Most likely problems in order?

Worth having a dealer read any trans codes?

Which solenoid engages Reverse?

Any links to trans documentation?

Thanks for your help!

[88yjproject]

Which engine do you have?

[TestPoint]

Sorry, 4.7L V8

[shockracer]

Have you tried going from park to reverse, and/or 1st to reverse? Just seeing if its a linkage problem. Also do you know if it was just a filter change or was it fluid and filter change?

[narnwv]

If it were a sensor, it would throw a "P0700-Generic Transmission code", in which a dealer would have to investigate.

Shift solenoid engages reverse.

I've gotta say that I've never ever seen anyone have trouble with the 545RFE transmission. In stating that, they're pretty cheap to replace, as there's TONS of them from wrecked vehicles (it was used in about 10 different vehicles), so they're everywhere.

After a bit of googling (again, never heard of a problem with this trans) I found this:http://en.allexperts.com/q/Dodge-Rep...ny-reverse.htm It applies to Rams, but it's the same transmission. Since you picked it up cheap, it may be worthwhile to have the dealer look at the software on the Transmission controller.

[88yjproject]

Also check the filters. A cracked filter could be your problem or a cracked valvebody. Drop the pan and look.

[TestPoint]

Spent an educational morning learning about non functional reverse.

Transmission codes read out as:

P0736 JEEP - Gear Ratio Error In Reverse Gear

Possible causes
- Low transmission fluid level
- Dirty transmission fluid
- Shift solenoids
- Transmission mechanical problems
- Transmission hydraulic control circuit

P1715 PG Assembly Malfunction/SSB Inductive Signature Malfunction

Possible causes ???????

P1790 TP (Mechanical) Circuit Malfunction

Possible causes ???????

Discussion with a Jeep technician resulted in his advice to change the transmission filters . . . and use factory filters. He says that he has seen aftermarket filters come apart.

Since the reverse requires 250 psi pressure vs the 125 of the forward gears that a clogged filter may well be the problem. Suspect that the previous owner's efforts at ATF replacement was done with a 'flush' rather than a drain and replacement of filters.

Found used transmission for $500 with 63k miles. Reman valve body for about $300. Going to go for the filters first.

Additional comments appreciated.